Day 33 bfn - did it take you long to get a bfp?

Hi, i'm on day 33 and ive NEVER gone past day 31 without my period. i'm a little underweight, 5'5" and about 95-98 lbs i would guess - could this have anything do do with why i'm getting bfn's? i'm really hoping that i'm pregnant and didn't take a test today because i don't want to keep being disappointed. did it take any of you ladies longer than expected to get a positive result? if so, how long after your missed period did you finally get your bfp?