i need more opinions on this. please..?

[rosieee.]

okay, so i'm about 3 days late on my period. i had a uti (urinary tract infection) last week. my boyfriend has been really worried about getting me pregnant and it made me worry a bit. i have weird stomach pains that feel like cramps but they are just a bit too high, they accompany my occasional cramps though. i took a home test and it came out to be negative. what could the reason for this be though?? i'm pretty freaked out here.

i took antibiotics for the uti. and we use condoms. my boyfriend really freaks about it though and it stresses me out hellatiously. i'm 16.