Being young and scared

I am 26 years old. I have had two miscarriages and the last one was back in july of 2018. I feel that its my fault that i lost them. My fiancee and i havent really had sex since i lost our son back in july. Mainly do to medical issues on both sides. So at the new year we decided we were at least going to try and do it again. So i started just tracking my cycle just to see. So the week i was supposed to ovulate we did it two days before my actually ovulation day, on the ovulation day, and two days later and then a few days ago. Now granted my AF is always on time. I am 25 days late but all tests are negative. But then again i was on a fluid pill and the brand i was on can cover up hCG in women. So on the 21st of February the medicine should be fully out of my system. Now the kicker is i have been sick, everytime i eat it comes back up. I have all the symptoms like i am preggers, but yet all test say negative. IS THERE SOMETHING WRONG WITH ME? I mean my fiancee and i werent really trying but we werent being protective either.....i want a baby and so does my fiancee but i dont know if i am or not due to every single test including blood test says negative. So what is wrong with me? Any help please and thank you.