I need advice about my boyfriend! trust issues...?

okay, well, my boyfriend used to smoke weed alot.like not just once in awhile...like multiple times a day. when we started dating a year ago i told him that i didnt like it and he told me that he would stop. i personally do not smoke, and dont like it too much, especially because he is 17 (i am 15) and he has very bad heart problems.throughout the past year ive caught him smoking weed and cigarettes every now and then, and he's recently stopped smoking weed within the past 4 months. he smokes cigarettes on and off, and he finally promised me that he would completely stop today. But here's the problem: all of his BEST childhood friends smoke, and they are all his next door neighbors. he can drive as well. i have nothing against them whatsoever, they are hysterical and kind people. but he spends excessive amounts of time with them without contacting me and ignoring my calls/messages. when i finally reach him he says he was just 'chilling with the guys' or that i need to chill because nothing is wrong ( meanwhile he hasn't contacted me in 8 or 9 hours...) his best friend specifically (Chris) smokes at least 5-6 times per day, and always encourages my boyfriend to do it when he knows that he is trying to stay clean from it.he has told me that he cant hang out, and then i find out that hes actually hanging out with the people who excessively smoke. It is not my place as a girlfriend to tell him who his friends should be, but he has no friends that don't smoke so it makes it difficult for me to trust him. I love him to pieces and do not want to lose him. And I don't want to be a controlling or sound psychotic, but in order to trust him, what should I do?I need advice about my boyfriend! trust issues...?
u r in trouble as he might not stop smoking and might as a result of u putting such pressure on him decide to either cheat and or hide other things from u which in due time cause the two of u to break up. let him be. u have tried ur best - let him do as he wants .. just tell him not to smoke around u - when u get that done - then u try and do other things slowly and not forcefully cos u can loose him all together for trying to change him