is my babee girl prego?

hi, okaie so hear is my storie me and my grirlfriend had sex last nigh it lasted up to about 3 hrs came all over her body in her mouth and every were we woke up this morning and my girlfriend had really bad moorning sicknes and was complaning that she had sore brest and she has been haveing these mood swings alday i tell yh its anouying to put up with but i was woundering if any one thinks she could be prego i mean were only 15 aND WE WERE AT A PARTIE LAST NIGHT N GOT BORD O WE DESIDED TO COME HOME AND HAVE SEX.. but i talked to my girlfriend and said maby you should take a prego test so im going to the shops with her tomorrow to buy 3 test i mean were are kinda responsable teenagers ? like we have never had sex untile last night we have been dateing for 3 yrs and she finily wanted some actchion i wasnt not going to disagree there because i was just as bad but i mean we have good paying jobs and would like to start a family one day if she is prego i am going to be there for her every step of the way !!! but i would really like some advice on what i could do to help and not make her go rage at me and also some advice on what some symtoms are of her being prego

thx :)