OK, first of let me say as someone who has been there and done that, your work is certainly good enough for the subjects you are shooting. A long time ago I shot senior portraits as well as weddings for a studio in Knoxville, TN.
The first thing you have to realize is that many "pros" are SNOBS! Openly admit that you specialize in school portraits and weddings and you are usually immediately stereotyped as just another photo-by-the-numbers hack. Rightly or wrongly the "shopping mall studio" has tarnished many good photographers by proxy.
Also, you need to find a website/group that concentrates on your genre. I havn't looked but there is certainly a forum for senior/school photography. I know there are forums for wedding photographers. Please understand, I'm not tryin to say that PF isnt the place for you, but to get meaningful advice/feedback from your "peers" you need to be talking to folks who shoot what you shoot. Don't try to get helpful advise or feedback on senior portraiture from guys who shoot pro sports. In the meantime (and longer) we're here to support you of course.
Anyway, as for your photos, are there nagging little details that could be better? Of course! But you will find those in anyone's work. Even the pros don't get every shot right, and frankly you probably sell more photos than 90% of them.
For someone with "no training" you are frankly doing amazingly well. You seem to have a knack for connecting with your subjects, especially the seniors/teens. You appear to have worked with them in the clothing they brought and have made photos that fit their personalities.
The wedding photos look a little awkward but probably only to another photographer. As you say, your clients like your work and if they pay for the prints then you've done your job. The measure of commercial success is the payment you receive for your services so if they are payin you are doin good.
The next test of success is, of course, referals and repeat business. Have your past clients sent you new clients? Don't expect this a lot but you should see some. After the wedding do they call you for holiday photos or special occasions? Again, you probably won't see a lot of this but you should see some.
So, if you ask me (and you did), I'd say keep shooting until you can't get clients, or you no longer enjoy it. Hope this is helpful. Good luck!
Mike