Our donor is 27 and has a son of her own, but has never donated. She produced 42 eggs for us, I can't remember now how many fertilized (it's on a post on this board somewhere, though), but we transferred 2 at 5 days and have 11 frozen, and I am pregnant. I think you have very good chances with someone 21. Our clinic does a lot of testing on women before they are allowed to donate, as I think all clinics do, but you might want to ask RE about tests of her hormone levels, etc. If you like her otherwise, and don't see a proven donor that you like as well, I would go with her, but that's just me. Go with what seems right to you, dh, and re. Good luck!