why me?

Am I the only one that gets there period and cries for hours? We have been trying for a year and a half now to give our three year old a sibling. I just don't get it. I am in the best shape of my life, I eat right, work out 7 days a week, track everything, and have sex at the right time. Still nothing. If I am not pregnant this month I'm going to lose it. Social media kills me! Every time I turn around someone is pregnant or having a baby and I can't help but get jealous. I went to the doctor and she said to just keep trying. How long is too long?! A year and a half seems like an eternity and I'm giving up hope. I just want one more, one. Sorry if I'm complaining too much, I just feel like I have no one to talk to about this except my S/o and he's just as upset as I am.....