Sucky, crampy, sore head....

How early can you detect/feel symptoms of pregnancy? I’ve been trying for four years and currently awaiting IVF. I ovulated a week ago....is it too early to be experiencing symptoms?? Is it just in my head? Already did a test but it was negative....

Advice?

Might just have a little bug hanging about me but been quite sick feeling, strange cramps, sore head and very irritable...probably just my period?!?