Is it possible to get pregnant 2 days after your period ends?

The first day of my last period was July 15th, 2010. I had unprotected intercourse on the 11th and the 20th of July. My period usually comes around the 22nd of each month and lasts about 5-6 days. In July, it came on the 15th and only last about 3 days. On the 20th, I gave my partner a condom but he took it off without me noticing somehow and I am not entirely sure if he ejaculated inside of me or not. I am a few days late this month and am unsure if pregnancy is possible or not considering the last time I had unprotected sex was 2 days after my period.

My breasts have been extremely sore and I have noticed that I've gained a few pounds more than normal and my breasts have gotten noticeably fuller and bigger and are extremely tender, along with bloating in my abdominal area. I've also had slight cramping in my lower back, but nothing unbearable. I always wake up in the middle of the night and in the morning extremely hungry, and I become extremely hungry at night, even after dinner and dessert! As I sit here typing, I'm thinking about what to have for my next snack. Before I go out and waste money on home pregnancy tests, I was wondering if anyone could give some insight on the possibilities of becoming pregnant 2 days after the end of my period. Thank you! :-)