This forum has a whole wide range of members, from those who get migraines a few times a month to those who get them every day, all of the time (including me). But regardless of the level, it's always good to have support with something so painful.
I'm afraid I don't understand what exactly you're asking when you ask if you're underestimating how strong your daily headaches are. Do you mean to ask whether your situation is uncommon or whether your particularly bad headaches make your daily headaches seem lesser by comparison?
As far as the first question goes: yes it is uncommon to get daily headaches. Relatively. Generally the phenomenon is known as "Chronic Daily Headache", and there are a large number of cases (enough for quite a bit of attention to be paid to it in the migraine world), but a pretty low percentage of the overall population. Though, if you frequent headache boards like this one, you may soon find that you run into a lot more people who have headaches like you do than you might have expected. Regardless, it's a condition that requires frequent and regular treatment by an experienced neurologist trained in headache treatment (or a team/clinic), psychological care (constant pain has a huge affect on the mind, usually sooner AND later), and frequently many different medications at sometimes very high doses (just remember, usually it's easier to deal with an unpleasant side effect than constant pain). Many of us see a lot of the hospital too, whether it's the ER or a planned inpatient stay of several days to several weeks.
Generally, the strategy is to find a drug that you can tolerate taking daily and find the right dose so that your headaches are both less frequent and less severe. It's a process of trial and error that can take anywhere from a short period of time to years (it took 5 years for my headache specialists to decide that they had tried every drug & treatment that they had available to them). Over this course of time, especially while your doctor(s) search for a proper preventative, you'll be given drugs to take when your headaches get particularly bad, like the Vicodin that you mentioned or drugs like triptans, NSAIDs, steroids, and antipsychiotics. The overall goal will always be to give you as much headache-free time as possible. Until that solution is found, however, any reduction is a good thing, though you may find a drug that can control your migraines almost entirely.
It's not all hit or miss always though. Aside for searching for a drug or treatment that prevents your headaches, specialists often take an approach of trying to "break the cycle." Through the use of strong, short term acute treatments like steroid tapers, nerve blocks, IV infusions, Botox injections and much more. The hope is that, if by using these strong treatments that cannot be sustained over a long period of time they are able to give you even a day or more of headache relief, that your headaches will drastically reduce in frequency as they were able to achieve a block and reset or slow things down. That's not to say that it's all or nothing, however. Even if you have trouble finding a drug that relieves as much pain as you want it to, the long term use of daily drugs with at least partial efficacy can have a (sort of) healing effect on your head. In other words, there are a lot of options, though the first goal may be to stop the ER trips--many headache specialists feel that going to the ER can be a bad thing as the doctors there are not specially trained or versed in your case history.
Anyway, it's very likely that you'll have a solution soon and won't have to suffer from constant headaches for too long. Some of us do but there are also plenty of people who get persistent headaches for some sustained period of time (a few weeks, a few months, etc) and they don't stick around. Make sure that you're getting the best treatment possible as it's a tough situation to be in, but know that you will get better.
DX: NDPH, Recovered CRPS
RX: Lamictal, Provigil, Clonazepam, Ambien CR, Emsam, Namenda, Oxycontin, Oxycodone
PRN: Haloperidol, Zyprexa, Lodine, Zofran, Skelaxin