To OP:
Do a dangerous thing... read your history.
The 18 year old age of majority is a (relatively) new thing when it comes to the grand scope of human history.
Just over 50 years ago, it wouldn't be considered strange for a high school girl to be reading a bridal magazine because more than likely she would be walking down the aisle and starting a family in a couple years.
Just over 100 years ago, girls getting married at 16 would have been considered normal, even in the USA (and certainly in the 'old country').
Go back far enough to the point where the average lifespan was 30-40 years, and you had better believe families were started as soon as girls were physically capable (we're talking prehistoric times here, folks).
What is IMPORTANT to realize, though, is that while we have raised the general consensus on age of majority over time, we have also changed the way we raise children. Go back to rural America in 1908, and you could find boys of 16 fully capable of running the family farm in their father's absence.
Were these boys different than boys you'd find today? Hell yes, they were, and the reason is because they were raised to be able to take responsibility as soon as possible. Every work-capable child meant more success for the farm, so there was little room for molly-coddling children. Leisure was scarce and discipline was harsh, but families turned boys into men and girls into women far faster than we do today.
This also meant life generally sucked for them. They *earned* the right to be treated like adults, because for all intents and purposes, they were. You can't gain maturity if all you're doing is going to school, playing some sports, and then listening to your iPod and going online the rest of the time. Growing up requires hard work and sacrifice - it's just the way life is.
That's not to say you can't be "more mature" at 17 than some folks are in their 20s and 30s. I know fully grown men today who have less maturity than I did in high school. It's a matter of your own life experiences.
Personally, I'd say take a good look at your life and personality and imagine for a second how they are going to change over the next few years. Do you honestly believe that you've become the person you'll be for the majority of your life? If the answer is yes, then you're ready for a relationship, no matter what the age of the other person. If not, than that doesn't necessarily mean that you should break it off. Rather, wait, and give yourself time to establish who you are. If the man in question is a good man, and he likes you for the right reasons, than he should have no issue waiting.
I left home and went to a boarding school when I was 13. So, while I wasn't fully making my own way in the world (I wasn't paying for myself), I did mature faster than average. Back when I was 17, and I graduated from high school, I think I was maybe 80% of the person I am now at 25. While a lot of the underlying foundation of who I am was already set, there was still a fair amount of change to come. Certainly, the next four years would see more 'seasoning' of the person I am now.
Could I have handled a relationship at 17 with someone much older? Yeah, I think I could have. There was one teacher I had in particular with whom I would have *gladly* welcomed such a relationship, but I can't honestly say how it might have turned out. I might have matured greatly and learned a lot from such a relationship, but at the same time, my lack of experience might have caused the whole thing to blow up in my face and become a painful memory.
That's my own experience, use it as you will. Back to you...
I would hope that your mother would have your best interest at heart. Unless she is a huge exception to the rule, she cares about you. Some parents don't listen at all, and if that's the case, there's not much you can do. But most, when any immediate threat is out of the way (such as your boyfriend), will listen and give their advice. This is something you should seek. She's been down the relationship road before, and (ignoring age for a moment) should be able to show you if his intentions are pure or not.
If she can't get over the fact that he's 30 to even *talk* about his other attributes, well, you're out of luck and need to find another trusted confidant. Bottom line, you need to discuss the whole issue with someone who cares about you, and who knows you well enough so that he or she can give good advice. Also, this shouldn't be a friend your age. This needs to be someone older who has at least been in one or two relationships.
As for the man in question, there's not much more the two of you can really do until you're 18, or until your mom comes around. For now, get word to him however you can. He's going to have to wait. As I said before, if he's a good guy, this won't be an issue.
While it sucks that he lost his job, you should not feel guilty because of it. He knew the risks, and should have been prepared for them. Believe you me, in the choice between the woman he loves and his job... a good man will choose the woman in a heartbeat and never look back. Don't think that you owe him something just because he got fired.
