I can understand your pain and this post is so relatable!
Since I became sexually active too, I have always had it. I was 16 the first time, and it took me ages to know what it was, as it almost became normal for me, as I questioned "did everyone get this afterwards". Not knowing what it was at that age, I felt embarrassed to go to the doctors. Eventually it got diagnosed and has been a recurrent thing for years, on off. I am now 21 and it randomly comes and goes. I have to be really conscious about what bath products I use, and how much water and alcohol I drink. Sex is also a trigger for me and I never know if I will be suffering afterwards. The amount of times I have had to restrict sex from the partner I have been with whilst recovering/on medication where doctors advise not to. It can be very frustrating for both!
I agree that even in sex, if it is going on a bit too long, I end up worrying about what it is doing to me and how I will be afterwards! Not where you want your mind to be!! With an ex, in the end I had to tell him, I can't go on any longer than X amount of time! But he knew the pain I would be in afterwards, so it wasn't like I was being unreasonable.
I also find the simple things - like hugging after sex - a pain when you have to make sure you get up to pee straight afterwards... like you just want to enjoy the moment!
Being pregnant, I still get UTIs and apparently it is common in pregnant women, so being prone to it anyway, it was inevitable!
I do miss being intimate sometimes and it would be lovely to freely have it without worrying about the consequences! The last time I had sex, it was so bad, it sent me to the hospital! So I even feel guilty for having sex sometimes as if I am inflicting pain onto myself! And it rights off my days where I am in that much discomfort, I struggle to walk and go about my day to day business and any plans that I have! It can be quite depressing. I end up spending hours in a warm bath (nothing in it) as it can be the only thing that soothes me!
It really is just trying to manage it and do all you can! Which it seems like you are doing that anyway! What if you went back to using condoms just for the times where you fancy intimacy, so you are not missing out completely? And perhaps have sex on the days you are ovulating so it is not too much and your chances of getting pregnant are higher? And the self insemination thing is a good idea so you're not missing out on those baby making chances! It might be worth going back to your doctor to have a chat and see what they suggest - recurrent UTIs are so popular, they must have some answers, advice or medication they can prescribe you to manage it. No doubt you are probably doing all those things anyway, but just thought it was worth a mention!
I find the cystitis sachets you get (cranberry flavoured mixed in water) helps to alleviate symptoms. I was even advised by a pharmacist to use them as pain relief as the symptoms are the same.
Hope this helps, even if it is knowing there are others that experience the same thing!