12 DPO 3 Days late for AF

hi ladies..

so I'm 12 DPO and I'm 3 days late for AF and I am never ever late for my period.. I've taken 3 pregnancy tests since yesterday and all have said negative... Could I be pregnant and the hcg just not be strong enough yet? My SO doesn't know because if I am I want to surprise him so im kind of anxious and want answers already!!

Oh and I have no PMS or pregnancy symptoms except for yesterday I felt really sick right before bed, just thought it was because I hadn't eaten all day but then I ate and still felt super sick.