Pregnant from precum?

i have been on the seasonale birth control since july 2011. i NEVER have had a problem with it. in Novemeber i was sexually active with my boyfriend at the time. in the beginning of dec. he broke things off with me, and i just thought this was all from depression. the weekend before (wed-sun) we were very sexually active and the times varied on when i took my BC but i never missed.. so i just dismissed the symptoms i was having due to that. but it is now march and i still have the bloating, nausea, breasts are super tender, tired all the time, heartburn, discharge, gas (and gas in stomach) headaches, cravings, always being hungry, constipation, peeing a lot and so on. i took 5 hpts and all were negative, and one blood test about 3 weeks ago and it was negative. my dr said it was thyroid issues. but ive had these all my life and have never had these symptoms. she said in 3 weeks if i wasnt feeling better to come back, so i did and she is blaming my constipation and heartburn on my too much iron since im on an iron pill, but i have also been on this most my life too. but what about all the other symptoms i have been having? could i still be prego? she said again if nothing was better in another 3 weeks to go back in and they would do an ultra sound. i recently have experenced lower abdominal cramping but its not bad at all. and lower gas bubbles, but they are like big bubbles and some people say thats what a baby feels like when it moves and i have been experencing it more and more. ive had my mind off this all of jan, but when the symptoms didnt go away and i only gained more i started worrying more and i dont think its in my head cause i forget about it days until i have gas or whatever cause im so used to the bloating and everything else. i just need some insight! please help!!