How funny tavistock - I literally just posted on the same thing. I am 10 weeks pregnant and just got told I have prob got a heart shaped uterus, which means the same as bicornuate.
The way I am feeling about my second trimester is that I have to just approach it like the first, unpleasant as it is, everyone knows they have a high chance could miscarry for those first 12 weeks, and mentally, I just need to extend that to the next 12. Yes, it would be a lot shitter. But you only have the life you've got, and you just have to choose.
It IS very frightening, but if they know, they can monitor you. The window of delivering a living child that is really brain damaged cos of it - say 24 to 30 weeks - is quite small, and if you're high risk there's quite a lot they can do (stitch you up to keep baby in etc, or inject steroids into your baby's lungs to prepare him for early birth)
IMO a c-section is no big deal. Lots of hospitals have 40-50percent c-section rates, and the reality is that when you look at the evidence (long term incontinence with vaginal birth versus c-section risks) there isn't much in it. In fact, (in the context of my job) a gynae I knew told me his wife and all her female gynae friends had all had elective c-sections - and let's face it, they know the risks
It is also worth saying, that if you get through one pregnancy, subsequent pregnancies are lower risk, cos your uterus is stretched
All of this sounds glum - the fact is, plenty of women with what we have sail through it and don't even find out they've got this problem till birth, maybe the birth of number 4! But I really get how you feel. It is a bit shit and yes I am very stressed, so I'm just explaining my current rationalisation of it all. Just remember, so many of the poor sods who lose a baby at six months have no known reason - pregnancy is always risky
Let me know if you want to know any more!