Low Sperm Count

My husband has a low sperm count. We have been ttc for 2 months now. He used SpermCheck Fertility Test and the results showed he has a low sperm count. We have been having sex everyday, sometimes more than twice a day (high libido for both of us). Is the low sperm because he doesn't have enough time to build his boys back up or is it because he is overweight? Is it impossible to get pregnant if a man has a low sperm count? Internet resources are conflicting. Also, since he had childhood obesity is it possible that he is impotent? He was 300 pounds last year, and has been overweight his entire life, as early as 5 years old. He is 5'11 250 pounds and I am 5'3 105 pounds so I empathize with his weight struggles because I struggled too, only I was the opposite side of the spectrum. I recently saw OBGYN, and besides being put on a high fat diet so I can gain weight for conception, everything is fine according to the doctor. He is taking ovtc testosterone supplements as instructed by his doctor, but his doctor says testing his fertility is unnecessary because he is young (23). I am 27. Any advice is welcomed.