Can we last? Do relationships this young usually last?

I have a boyfriend right now and he's 17, I'm 16. I remember the first time we talked, we got a long SO well which is rare for me because I usually get bored of people fast. We have so much a like and it felt like we've known each other since forever. We started dating a couple months after knowing each other and currently we are in a happy relationship. However, it is hard at times because I have unstable relationships with people. By that I mean my dad *most* of the time. I don't have an unstable relationship with my boyfriend but I do make it hard sometimes. I have Borderline Personality Disorder and am currently getting better from suffering from major depression. Anyway, he is the most amazing person I have ever met. We make each other happy, we accepted our flaws and we're just very happy together. However, I do have a bad habit of thinking of negative things that can come from good things. I want to last with my boyfriend. He makes me feel a happiness I haven't felt in so long. I know some of you are going to say that we need to "experiment" with other people which is true but we both already know what we like and dont like and what we want. He's been sexually active before and I've been with guys before too. I'm just scared of losing him and I guess I want some reassurance that we can make it together. There's a couple at our school that have been together since 7th grade, they are both now juniors and I admire how they have been together for so long. What do u think?