I can't say that I had lower back pain when I had a bad gall bladder, but other than that, your symptoms sound very much like mine. I would sometimes hurt up into my right shoulder/arm/elbow. Feeling like you're overly full after only a small amount of food is very common with gall bladders. I would get halfway through dinner and suddenly feel like I had eaten about three bites past the "full tank" mark.
And getting up in the middle of the night is very common of gall bladder attacks too. My usual time to get up was around 2am. I would get up in terrible pain and nauseated. The pain was so bad I couldn't stand up straight. My pain was all along my diaphram, although it is more common to hurt specifically on the right side. However, in some people (like me) the pain radiates to other places. I would pace the floor because pacing seemed to help it a little. Eventually I would work up to an almost explosive diarrhea episode, where the diarrhea was yellow and burns (excess bile in it). After I had passed one or two stools, then the pain would start to subside. I would crawl back into bed--the whole attack having lasted about an hour--but I would still be sick enough that I couldn't lay down; I had to go to sleep sitting up. I would always be very tired after the pain had passed, and during the worst of it and afterwards I would have the chills very bad. Being where you can't lay flat on your back when you are having an attack is VERY common. In fact, it may be the most universal constant of a bad GB; I haven't met anyone yet who could lay down when they were hurting and sick. The other symptoms can vary from person to person (some people are full of stones and don't even have symptoms at all).
Vomiting is also quite common among people with bad gall bladders, although I only did it at once. Some people are diarrhea-dominant, some vomiting-dominant and some do both in fairly equal measure. I always had diarrhea when I was having problems. Also, I had problems feeling like I had trapped gas, which may explain your back pain. When I developed a bad gall bladder, I suddenly quit passing gas and burping. It's like it all got hung up inside and I would have stabbing gas pains and I longed to be able to pass gas. I would have done it in public if I could have, it was so bad sometimes!
I did find a heating pad/hot water bottle did help relieve the stomach cramping a small amount, but it had to be really HOT to do any good. I'd keep a heating pad on high or, when I was in Ireland, I would put boiling hot water in a bottle and use that. Obviously you want to keep at least one layer of clothing between you and it and move it around and take a minute's break every 5-10 minutes or so you keep it on. Basically get it as hot as you can stand without burning yourself. That helps relax your stomach muscles some and will combat the chills. Unfortunately it won't relax the gall bladder any, but a little pain relief is better than none at all.
One other thing I noticed as very telling in your statement: your eating pattern for the day. When you have a bad gall bladder, don't go for a long time without eating. For a long time I never got normal hunger pains; I went from feeling neither full nor hungry to feeling sick and having stomach cramps. Someone I work with who has had her GB out too said she had read that the gall bladder regulates appetite and that when it's not working or is gone, you have a hard time knowing when you are hungry. Learn to eat regular meals at regular times and always have something with you at all times that you can munch on if you start to feel a little sick. If you have this problem long enough (I had it for 5 years before I got mine out), you'll learn what pain/sickness means hunger and which means stop eating. If you suddenly feel full after only eating a small amount, then stop eating immediately. You'll only feel worse if you try to cram some more in. After the feeling/attack passes, then you can get another meal (learn to get a to-go box and eat leftovers). And when you're having an attack, eat only when you feel like it. I had an attack that lasted three weeks solid and all I ate was a bowl of Corn Pops once a day. But, when you are feeling okay, keep up regular meals to keep from feeling sick and hurting all of a sudden. Because, like I said, if it is your GB, you won't get normal hungry feelings. Also, eating regularly will help cut the heartburn--which can also be a sign of bile refluxing up the esophagus.
The other thing about your eating pattern was the coffee. You better learn to do without that right now. One, it's really bad for acid reflux because it is so acidic itself. Two, caffeine is a trigger for a lot of people with bad GBs. And three, coffee can bother anyone to have it on an empty stomach. Caffeine was a MAJOR trigger for me. Took me years to figure it out, unfortunately, but when I dropped it, I went months and months without a problem. Luckily, I wasn't a coffee drinker to begin with, but I did have some issue giving up the cokes. I also had to give up my grandmother's black tea until she switched it to decaf. Depending on your sensitivity, you may have to give up herbal teas (although they generally have so little that they have never bothered me) and/or chocolate. Since I've had my gall bladder out, I've had times when I could have a can of coke a day and not have any problems. Then I take times when half a coke will do me in. I've finally just given up the idea of ever having caffeine again (except in herbal teas and chocolates--which don't seem to bother me at all).
The other thing that bothers a lot of people with bad GBs is carbonation. So even if you get decaf coke, you may still have the trapped gas pains caused by the carbonation. And you'll have to stay away from fizzy waters and the like, too. Finally, you have to avoid alcohol too. Like coffee, it's not good for anyone with acid reflux, nor is it good for people with bad gall bladders; so whichever you may have, it's bad for you. Some people with IBS find that beer and wine and wine coolers are all bad for them, but they can handle a shot or two of hard liquor. I don't know anything about that because I've never actually had any hard liquor, but I had the occasional Bailey's Irish Creme while I was in Ireland, and that didn't help things any. Better to stay away from all of it all together. What's that leave you to drink? Water. I drink a lot of water. If I get bored with it, I may make myself up some Kool-Aid. Or green or black tea (decaf). Decaf coffee is still acidic, so avoid it. Avoid juices too since they are acidic and won't do your esophagus any favors either. You can use a little juice, though, to flavor up water if you like that sort of thing. It takes some getting used to, but you'll eventually be content with just plain water. I almost never drink anything else now. If my fiance didn't keep bring cokes into the house, I wouldn't even miss them, but when they stare me in the face every time I go to the fridge, I do long for them sometimes.