Unexplained Infertility???

So I went to my doctor today after having my HSG done and my husbands semen analysis done. His semen analysis came back perfect and my HSG showed one side (left) opening up and normal and the right side wouldn't open. I've never had any infections or surgeries down there so he thinks it could've been a spasm. I've always been regular with my periods up until this July and I just never got one. Then I got it in August and didn't get it in September or October. He put me on Provera so I could jumpstart my period before I got my HSG done this month. He said he doesn't think I have PCOS because I've been regular all my life up until now. So the only thing he can think of is a hormonal imbalance. But what could cause that to start messing up anyway? I'm not going to sugarcoat it. I've never been a small girl. At the moment I weigh 252. I've gained 54 pounds since I've been with my husband over the past 3 years. I'm thinking maybe gaining that much in almost 3 years might've put a problem on my hormones. Idk. But he said this is unexplained infertility due to me having an patent tube and ovary and my husbands sperm was good.

So, he is going to put me on Clomid 50mg and titrate it if needed. Did anyone else have a problem similar to this and got pregnant?

Also, I've taken many OPKs but always came out negative. How is that possible if I had regular periods up until now? Don't you have to get your period in order to ovulate? I'm confused.

Anyhow, wish me luck and much baby dust and hope that Clomid works. He said it could take up to 10 months with Clomid to work and after that he will send me to a Reproductive Endocrinologist.