I had my surgery almost the same time as you. Oral meds never worked for me and gave me all the sideeffects you said: a feeling of congestion in the head and I had vision changes, like a blue halo which I didn't like at all. So I've been using trimix for 6 years now. My worst experience was from the first injection because the MD ordered too much. He ordered like .20 ml and I had the 4 hour aching erection which I packed in ice, thought I was going to the ER but didn't. After that I got real smart and started with .05 ml, no reaction, then .08 ml, a little reaction, then .14 too much again, 4 hour deal. But that time I learned about
getting the behind the counter sudafed that has the active ingredient you need to bring the beast down. I have now settled into .13 ml which seems to work almost all the time. You have to remember that your solution may weaken a little with time so what you need today may require a little more in 6 months. Plus the needle position does affect the response. The ideal injection spots are at the 10 and 2 oclock positions on the penis, they want you to alternate your shots to prevent curvature. Sometimes a little more of the solution gets into the corpus cavernosa so the response is stronger. Plus trimix is very strong and is weird in that just a change in 1 ml can have a dramatic increase in response, ie the 4 hour erection.
The length of the needle makes a difference too, I always use the short, orange colored diabetic needles, the small guage ones. I have developed a slight curvature to the left, ie Peyrionees Disease so I always inject on the R side because any scarring cause the penis to bend towards the scarred L side. Peyrronies Disease is rare, may be the result of prostate surgery itself, maybe from injections, no one really knows. My curvature is minimal and does not affect intercourse so it's unlikely you would get this but who knows.
After 6 years of using trimix I feel pretty comfortable using it and don't fear it all like I used to. There also is bimix which some guys use because the aching you initially get from trimix is less. I don't get the aching from trimix anymore maybe because I'm used to it.
The really big question you have to ask yourself is learning how to do the injections worth it versus getting a penile implant. On frank talk they can tell you all about implants. Everybody whose had one seems to think they're great so maybe that's the way to go. Injections do work and with a less practice are predictable, but there is really no spontaneity with injections which to me is the big drawback of using them. I mean you have to go to the bathroom, inject, wait 5 minutes, come out do your thing and then wait at least 2 hours if your lucky before you can do anything. Some guys can inject at night and then just go to sleep but I found that difficult, so we have sex on weekend mornings. Obviously you can't get go to work with a bulge in your pants. If I was younger and hornier I might consider an implant but at the age I am now and with the frequency of sex my wife and I have anyway I don't think it's worth it to me. But it's something to consider .............