What does it mean if he doesn't fallow through with anything?

Hello, I’m Gabriel and I’m 14 years old. My boyfriend and I have been dating for 2 months and he is my first serious relationship. We’ve become very attached to each other and I would be heartbroken if something were to happen to us. I really want us to work out to where we can be together forever and I truly believe in my heart that it’s possible. I can see myself being happy with him forever. I want to spend every second with him and I think it’s the same for him, he says it is. He makes me so happy and when I’m with him I feel like I couldn’t ask for anything else. I get along with his friends and family really well and they all say that they are really happy about us. My friends don’t really approve of him because he smokes, but he’s been trying to quit for me so I’ve respected that and I haven’t complained and it hasn’t really been a problem at all. However, there is something we need to work out in order to keep our relationship going. We’ve been having problems with him not fallowing through with things, such as he says he’ll call me and then he doesn’t, or he says he’s going to pick me up from school and he forgets or something happens. I was okay about it for a while because besides this habit he is a really good boyfriend and treats me really well. But I went off on him today because on Thursday he didn’t pick me up from school again, so I walked to his house like I usually do when he doesn’t show up and he wasn’t at his house. I called him from a friend’s phone and found out that he had gone to a friend’s house to have a cigarette. I can’t even begin to explain how mad and hurt I was, I felt like he had chosen a cigarette over me. I don’t know if he just forgot about me or just chose to not pick me up but either way I was completely insulted and began to question if he really loved me (though logically I know that he does I couldn’t help but feel like if he did he wouldn’t do that) I yelled at him and then I told him I would call him when I cooled off, so I stopped talking to him and I’ve been thinking about it all day. I’ve been wondering why he’s like this and what it means for us. I came to the conclusion that I have two choices. I can spend the rest of our relationship over thinking our problems and having doubts about his love for me, or I can risk getting hurt, put all of my trust in him and just simply be with him. Since I’m not willing to throw our relationship away over something that really isn’t THAT big of deal I’m staying with him. But I know that I can’t deal with this being a problem anymore. So first I would like to know what your opinion on the situation is, and second: HOW CAN I FIX THIS???