Birth Control fail and had to take Plan B?

I got back on my birth control asap, but the plan b didn't induce my period, and Glow says it's not due for a week, but on my birth control they've been coming sooner and i've been having shorter cycles. My question is, could I be pregnant? I'm having some symptoms but I feel like maybe it's just me freaking out and thinking EVERYTHING that happens to me could be a symptom. Like my nipples have been sore, I haven't been sleeping good, but then I got really tired today and yesterday and slept a lot, i've been constipated, and i've been feeling kind of sick but that could be allergies. Thoughts?