LH and FSH when do you go get blood work done?

Geez I went to the gyno yesterday and he talked so fast and I tried to remember as much info as I could but I didn't. So I have 2 blood tests to do. One is the 21-day to see if I’m ovulating last cycle I was so we're just going to check again. And the other one is LH and FSH, I don't remember when he told me to test for that. Can I test the same day I do my 21 day one?? Also i'm a little nervous b/c he said if I get my AF this month it would be a good idea to do the HSG to see if I have any blockage.. Has anyone had this done??? Is it painful??? I’m pretty much welling to try anything b/c we’ve been trying for 3 years. We got pregnant in Dec 06 but lost it in Jan 07. It’s been a long road I just hope we get to be parents…Thanks ladies and gents