Missing period

So I am currently 16 days late. I didn’t have a period at all during the month of march, and so far there’s no sign of my period in April. There is absolutely no chance that I’m pregnant and I haven’t started taking any new medication that could possibly mess my cycle up. I’m just super confused, this has never ever happened to me. I have had a period every single month since I started having periods. My mom mentioned stress could be causing it, but it still just seems like a long time to go with no period. Has anyone gone through anything similar? If so, did you ever figure out what was causing it?