TTC for 12 years

Been trying for 12 years to get pregnant. My old doctor just said it was because I was fat. Lost 100 lbs still didn't get pregnant. Switched doctors she said needed to lose more weight. Now come on it can't be my weight so get a new doctor. Finally one that cares has done all kinds of testing on me. Everything normal or within normal limits.. Still not pregnant.. I've tried everything what else could I do try or just some suggestions?!