Missed period 3m pp??

Lindsey

Y’all I just had a baby in April and I got on the pill again at my 6 week check up… I had 2 normal periods and then one that lasted only 2 days. I’m now 7 days late. Pregnancy tests are negative. Is it normal for your period to be all wacky still after nearly 4 months? I’m a little thrown off because it was completely fine even after I started birth control again. I’m trying to not stress but my fiancé is worried I’m pregnant again and I’m fully convinced that’s not it.