Castaway: I'm sorry things have been so rough for you. I've only lost one pregnancy, and it was 11 1/2 weeks, not as far along as yours was. That being said, I can't imagine what it would feel like to be in that situation. I was wondering though, what if you just shrugged off all the stress of worrying about TTC. Just have sex, no supplements, no charting, no paying attention to anything? That way, either you get pregnant, or you don't. Just don't think about it. -- And then I understand that being pregnant is hard emotionally... so if you do, just try not to think about it.
A couple stories, to help you or anyone else:
Hairdresser: My hairdresser I go to occationally had 15 miscarriages before she finally had her baby. Some of them, of course, were chemicals. Some where blighted ovum's. Some stopped growing. Most were before 10 weeks along. She told me that she "gave up", and would just have fun without stressing about it - but did go into a big period of depression. She now has a 23 year old girl, her one and only baby. She stopped "having fun" after that, and started preventing.
German Family Friend: She always acting like she never wanted kids and hated them. Currently in her 40's, it turns out she TTC and gave up because she never was able to. Then she told herself and everyone else that she doesn't want to have them. She got pregnant recently, had a MC. Then got pregnant soon after again and had her baby.
So I know it's rough, but there is positive stories out there. It might be grim now, but there still is that silver lining.
Of course, do whatever you feel like you emotionally can do.