Boyfriend problem PLZ PLZ help !!!!!!!!?

basically ive been going out with my boyfriend for like 6 months. he was 16 nd i was 15 but hes just turned 17 now. anyways like when we started going out, like 2 weeks or something i heard that he had been askin my friend ( who he used to fancy and tried to go out with before i met him) to go places with him like concerts nd stuff.....nd i was like wtf but i dint take it seriously. anways then into the relationship about 3 months he was being all sweet one day and saying that hes got all my texts i ever sent him so he gave me his fone and i was lookin through nd al happy nd stuff, and then i see this friggin text from a girl nd i read the text that he had sent her and it was soo flirty nd askin her to meet up with him! nd this girl was his friends friend nd she was like 18! anways i got mad at him like let him know i was angry....nd stuff. he said sorry shes just a mate etc. then about a month ago i was on this website thing, its like a application on myspace type thing. its where u can send people smiles and love and write them comments. i was just on there one day coz i was bored nd i see that he was said to bout 10 girls hey ur so cute blah blah blah blah nd he also asked a girl where she lived. ok so basicly that is the main things that has pissed me off and made me feel selfconciuous coz if i was so pretty and she fancied me, why wud he do that. ino its only online but it feels weird that he dun that. apart from al that hes so amazin nd a really nice guy. like hes not those type of guys like playas nd to be honest thats wat shocked me so much coz i thought omg hes so nice nd stuff nd hes so special nd even now he tells me hes in love with me nd he doesnt eevn want yet he said wait till im 18. do u think im goin OTT bout wat he has done? am i being paranoise becoz ino i am paranoid. i feel like i cant trust him anymore :( i feel like hes gunna go cheat on me in real life ino im so stupid but i feel like he will.