8 days late but negative test

So I am 8 days late cycle length 38 days and I’m also 3 months postpartum I’ve only had one period since having my son and it was long almost a week that was from 3/31-4/5 Before having my third baby my periods were always on the dot, me and my spouse have been a bit unsafe but it was after my ovulation time around April 15th and it happened April 25th so that’s pretty far apart, I’ve been having bloating, mild cramps and discharge. Today I took a test and it was negative 5/7 I’m almost sure since it’s been over a week since my missed period it would have shown up if I was right?… I’m definitely not looking for another baby right now my spouse was supposed to get a vasectomy but hasn’t yet and we got drunk and yeah that happened sooo now I’m just stressing what it could be? Still regulating from having a baby? What’s the longest cycle length to rule out pregnancy? This is just really stressful