Hi, I had my Day 21 bloods taken today so I am a few days behind you. From what I have read on here and elsewhere, most docs consider 30 as confirmation that you have ovulated (and I know some poster's gynae wanted to see 40). So I am sorry to say I think that is a bit low. But I am no expert (just an avid reader of internet info!) so see what your doc says.
eurochick is right (btw if you're wondering of I'm stalking you, yes I am!). 30+ confirms ovulation. Don't panic though, my GP took 3 "21 day" bloods over 3 cycles because most women have a couple of anovulatory cycles in a year. I'd keep using the opk and ask to have them taken again.(don't panic too much, my friend's was 0.5! She now has two dc .
Apparently yes. Because the ov sticks just detect the hormone that surges in advance of ovulation. It doesn't mean that the egg definitely gets released.
Also, if it was 7 days after your positive opk, you were probably less than 7dpo because the hormone surge happens a day or two BEFORE ovulation. Although I was told that anywhere in a 5-7 dop window would be ok (I have just had mine done on 5dpo because for the second month running, 7dpo has fallen in the middle of a long weekend!).