If i get butt fucked will i get pregnant?

ok well me and my boyfriend Butt Fuc*ed about like 2 weeks ago.. and I was on my period. while me and him were doing that, I had a tampon in.. he didnt cum into me. although he was probably precuming a little bit. we were using lube.. and his precum prob. mixed in w/ it.. so after we were done and he cumed into a tissue, I went to the bathroom and I peed and changed my tampon, before a put anoter tampon in, I wiped throughly to make sure it still wasnt really lubricated, or untill it was dry. then I put the new tampone in .. but im thinking that when I put the new tampon in that the precum could of still been around the hole and I gotten on the tampon and then into me..
I dont really have a lot of symptoms of being pregnant… I actually just weighed myself, and I lost 5 pounds I do weirdly always have a sention that I have to pee all the time, but when I try to go.. I dont and when ever I like push into my stomach, it hurts and I get like a quick cramp PLEASE HELP ME!!!