Breastfeeding & Periods

Okay ladies, so my son is 3.5 months old. I'm exclusively breastfeeding & finally had my first period, which was a normal 5 days, last month. This month I haven't gotten it yet, but had all the symptoms leading up to it. Hubby & I try to always use protection or be super careful when having sex. Has anyone else experienced irregular periods while breastfeeding? Have you skipped a month or more at a time & not been pregnant? I really don't want to waste time on a pregnancy test if this could be normal. Thanks in advance!😊