I'm 3 months over on my Birth Control in my arm could I still get pregnant?

I still have my birth control implanted in my arm and it's been three months since I was supposed to take it out. And I've had unprotected sex since. Is there a possibility I could be pregnant? And my periods are way irregular. On one month I was bleeding for two weeks! Is there anyone with advice? My appointment for this was supposed to be two months ago but the doctor that specializes in birth control implants had left the clinic and there is only one clinic around my area. And I've made an appointment in a different area but that's not until January 25! I have stomach pains too.