Pregnant?

Okay, back story.. so I've been with the same guy for 4 and a half years. We've never really used protection, he either pulls out or doesnt. Well it took 3 years for me to get pregnant, I just always thought I couldnt have kids. But I had my twins a year ago. Now we've had some unprotected sex but we've been trying to use condoms as much as possible or pull out... that's where it starts.. my period is so irregular.. like I can skip months but not be pregnant so I just never pay attention to it.

I haven't had my period all month and the other day I wiped and there was some light pink on the toilet paper.. but that was it. No period ever came. The last 3 days I've woke up with terrible acid reflux and have had headaches.. should I be worried?