confused

I haven't had a period since a little after Christmas , I just took a pregnancy test at the hospital last week n it came out negative , I use to period calendars n both say I'm over 2 weeks late , last time this happen to me n I took a pregnancy test , it came out negative then I go month or so later n I was 3-4 months pregnant smh n this was 4 years ago I'm just scared this is gonna happen again or I'm just super stressed out or something I'm like never late even being stressed out a little I'm usually almost always right on time with what my calender says . But it's so hard to know cuz all the times I've been pregnant I found out like when I was 2-3 months ..