It would be unlikely to have a negative at 6 or 7 weeks, but it could also be possible that you ovulated late and aren't as far as long as you think. Or there could be another explanation for your symptoms. There are a lot of tummy bugs going around. So really, without a blood test, there is no way to know. Out of interest, how are your breasts? Any discomfort, tingling etc? That can also be an early sign.

Fingers crossed hun that you get the result that you want.