Am I pregnant? no period for 3 months?

me and my now ex had sex back in march and i cant remember if i had my period that month before we had sex or not but i have yet to start. For like 4 or 5 weeks my boobs got really really sore and i would feel somewhat nauseous. i havnt taken a test yet because i was thinking i couldnt be since we used the withdrawal method and i had read somewhere you can not get pregnant from pre ejaculate. i also read that if done right the withdrawal method works very good and we had already been together almost 2 1/2 years and we have always used that method. Im actually rather scared that i am and thats why i keep procrastinating and not taking a test. im wondering what the likely hood of my being pregnant is