Is it ever TOO LATE to take a pregnancy test? The last time I had sex was 7mo ago, I took 3 test 2wks ago. All neg, but were they accurate?

Tests are accurate. Pregnancy happens only if you have unprotected sexual intercourse around the time of your ovulation (a few days window) when you have a mature egg ready to be fertilized. Neither the egg nor the sperm survives more than 3-5 days. If you had no recent sex, there is no need for pregnancy testing.