have you tested yet to see if you are, if it comes back - I would see your GYN.
I agree with Becca323, because you had a lighter period in March, that may have been why you had a heavier period in April. The sore breasts could just be the you are ovulating soon or that you already have, and it's also a sign of PMS.
unlikey. if you didn't have a period in April or a very light period, then i would say possibly, but it could very well just been hormones a factor in this.