Possible may be pregnant? Help!!!?

My husband got his Vasectomy in late November. He was ordered to go back and give his 2 samples. He never ended up going....ugh! Am late for my period. I feel tired, bloated, my were hurting and itching maybe 2 weeks ago. I went to the doctor because I had a fast heartbeat they didn't know why. People say you can when your pregnant due to the blood volume. My sister was saying that I look pregnant! I just read that when a man has a vasectomy that sometimes the sperm still can live and will take about 15 times until there is no sperm left. Am so nervous! We have a 10 month old and a 2 year old! Anyone been threw this before? thanks so much:)