24 years old and keep gaining weight....

Okay so we have been ttc for 4 years and 3 years ago went to a doctor to get checked. Everything seemed fine. Well since May of 2017 I keep gaining weight. My diet hasn’t changed if anything it has gotten better, and I have been going to the gym 5 days a well, for the most part. I went from 145 to 172 all in a span of 8 months. What is going on??? I know muscle weighs more than fat but my body hasn’t went down or toned up to much.... idk what’s going on. We start to go back to the fertility doc on the 24th, and I don’t know if I should go back to my regular doctor and ask them(they are military doctors so they arnt always there to help).