PMS vs Pragnant??

Is there a way to tell the difference? I'm not very regular because of the birth control I'm on. I had 2 periods in a row last month and bled from like the 23 of December to the 8th of January. I haven't started my period yet this month and I'm starting to freak out. I feel my normal PMS stuff like sore boobs, etc. and nothing feels out of the ordinary but I know those things can also be signs of pregnancy. Any way to tell the difference? It's a little too early for me to be able to take a test yet.