Depo and pregnancy

Okay so my depo shot finished on the second of February this year and it's been about two months and my breasts have been quite sore, I have read this is a symptom of coming off the depo shot and I have not been on birth control since and I have been responsible and using condoms, is it the depo giving me sore breasts do you reckon or am I pregnant? I also had a period that was quite heavy an started on the 18th and finised on the 22nd of March...am I being paranoid?