Hi Hun, I understand the process you are going through as we have been there ourselves. It took us 2 years to conceive and to give you some hope, I am now 23 weeks pregnant.
My partner's tests all came back normal, my bloods normal. We have Normal weight range, neither of us smoke. My cycle was regular, although I would have a brief period, 2-3 days max, but painful too.
I had an internal examination, everything ok there but they did discover I had poly cystic ovaries, the cysts were tiny and there weren't many of them. Now I've not had symptoms of PCOS other than that over the last few years my energy levels have been lower than usual and that I had to work extra, and I mean loads extra, to keep my weight down. But I put that down to simply getting older.
Anyway, they did further tests and I was diagnosed as being insulin resistant. I was put on a dosage of metformin and was pregnant within 2 months. Apparently insulin resistance and PCOS are linked and they cause irregular ovulation. The metformin restored that - clearly!
You may have been checked out for all this, but it's worth knowing if not. Good luck, and try to stay positive, I know that's much easier said than done. Also don't be afraid to push and push for more tests. Take care xx