Normal regular periods, now 8 days late and negative results!

Hi. My story been ttc for 18months, done the vitimans, conceive gel/pre seed, regular bd, not wanting to stress me or my man out and taking over our lives. It's hard watching all your friends conceive so easily doesn't help. Only a few people understand what we see all going through. Well I'm currently 8 days late on my regular 31 day cycle! Cramps and far as I can tell high cervix, but so far negative tests (using testing strips) I brought the dearer ones once before but don't want to waste my money untill I know the chances are higher! I hate feeling so confused just want to know either way! Any one else out there with negative strip tests or playing the waiting game!!??!?