Late Period-2nd month in a row

Lauren • 24 years old, mother to a beautiful 7yr old girl. Fiancé and I have been together almost 3yrs & we want a baby!!
Ok so last month I was 5 days late on my period, took a pregnancy test and sadly it was negative. Started and the first day was literally one light spotting, then extremely light the remaining 3 days. Well, this is the second month in a row I'm late (2 days so far) and I don't necessarily think I'm pregnant because I've been having normal period symptoms, but, opinions? Advice? Reasons I'm late again?! I do have an extra pg test I guess I could try in a few days lol.