Kinda confused

So I'm still new to this whole IF thang... and I guess I'm somewhat confused as to everything that's out there. I know my doctor/nurse will make sure I am where I'm supposed to be and make sure I am given the right treatments and what not. I guess I just feel kinda stupid when reading about other people's IF issues. Anyway. So my blood work came back from last Thursday and it looks like I'm good! My progesterone was at 54. I was told that was normal. Whatever that means. I'm trying to fond a detailed, easy to understand website that explains all of this stuff. Why are they monitoring my progesterone on my CD3? I know they'll do it again this Thursday also. I'm having another US to see where I'm at after the Clomid - I guess this is where they'll be looking at follicles? Hopefully everything will work out and we'll be good to go. My other huge worry is not knowing when I'm going to ovulate, if I do and how I can tell (since that's my problem - I don't). I know OPK tests are supposed to work but the last ones I used told me I did, when I didn't. WTF? The nurse had me buy a different brand, so hopefully there won't be any more confusion.