They were easy@home brand of ICs I bought off Amazon. 25miu. So, quite low. My first negative on that (of many) was aug 18. Nearly 3 weeks ago. I got positive opk aug 25 and 26am, confirmed with temp spike Aug 27.
I must seem so ridiculous to all of you being so paranoid! Thanks for your help and answers and reassurance. I agree that it would be highly unlikely, with negative tests for weeks to test positive. I read that FRER can pick up 6.5miu so that has me nervous, is all! Surely my levels would have dropped from below 25 (I got a negative test so must have been under that) to at least below 6.5 in nearly 3 weeks? And I O'd!