Could I be pregnant even though still feeding?

Hi. I've seen many of these questions on here so pretty much know that it's possible...but just wanted to get some thoughts. I'm feeding my 4 month old. I was feeding him exclusively for the 1st 2 months and then I went back to work and began to supplement with formula for the 10 hours a day I’m away from home (although pumping at least once during the day while at work). I did notice that my cycle returned about 2 & 1/2 weeks after I went back to work (and began supplementing 3 feedings a day with formula). I have not had my next cycle.....2 & 1/2 weeks late (now) and just don't know if I could possibly be pregnant AGAIN this soon! I've been having unprotected for the past month & 1/2 since I've been feeding and think that possibly I haven't started again due to my hormones and still feeding, etc....but am starting to wonder if I'm pregnant. I had some weird cramps a couple of weeks ago. Should I test or is it probably just my hormones delaying my cycle?