Cheapy ebay pg tests

I bought 30 tests from ebay for something ridiculous like £2.60 they are meant to pick up from 10 hcg or whatever it is well i still have no period after my coil that got removed 32 days ago had lots of symptoms but no bfp could they all be faulty? Taken 12 of them one each day as im so uncertain of my cycles now etc they used to be 21 days like clockwork its 30 days since i had light spotting x