Phentermine??

A little back story: I was diagnosed with PCOS a couple years ago and have since been trying to grow our family with no luck (I already have two children prior to the PCOS diagnosis.) I went to my OBGYN yesterday for my annual checkup and my OB told me I could lose some weight.. which I knew. I have about 50 pounds to lose. She told me that she thinks that if I could lose the weight, I’d be able to get pregnant. She brought up phentermine and told me she thinks that it would really benefit me and wrote me a prescription and I have yet to fill it. As someone who doesn’t even like to take Tylenol unless absolutely necessary.. it just makes me nervous. If I were to take it, it wouldn’t be a long term thing. Just 3 months. I’m not sure if this is the place to ask .. but I wanted to try. Has anyone taken it? Is it dangerous? Or worth it?? Thanks in advance!