How accurate are ovul. Tests? I am using clear blue one day I had pos LH surge on day12 my next cycle I had a pos LH surge on day 16 is this "normal"?

It depends. They can be very accurate, but - the more irregular your cycles, the less accurate they become. I can't make guarantees online, but i expect if you got a clear + each cycle, and if it was only one + in the cycle then the tests are probably correct. Cd 12 then cd 16 could be correct, but i'd expect the first cycle was shorter than the second?