Congratulations! That's a great score--it beats my best score by 30 pins. And since you're only 18, I'm sure you're destined for even bigger and better things.
I've bowled in leagues for 10 years now, and for most of that time, I was either the best or the only thumbless bowler in my league. Then last season, I bowled against a thumbless bowler who averaged 210, and there's a 220 thumbless bowler in my current league.
The 210 bowler used three fingers for spares and was probably a better spare shooter than most 210 guys. (I'd guess he'd bowled with three fingers for a long time before he switched.) He used his 4th and 5th fingers on the strike ball, which I didn't get at the time; looking back, I'd say he was trying to get extra finger turn, go from 7 o'clock to 3 o'clock.
He had very smooth mechanics and a big hook, but I wasn't impressed with his strike shot, which IMO had too much finesse for a two-finger bowler: not much speed, and the roll wasn't that heavy, either, so he left a lot of single pins. 100% of the difference between us was spare percentage, maybe more than that.
I was really excited to get a close look at the 220 bowler, but the big difference between us was obvious immediately--his regular strike shot runs about 20 mph. He gets a very heavy roll (the ball is wedged against his forearm on the approach) but his finger turn is the usual 6-to-3, and with his speed he's not much more rev-dominant than a typical bowler. He throws two-finger spares, but again, he speed allows him to pick up the 10pin by throwing his usual strike shot with a regular plastic ball, with no fear of over-hooking.
I'm at 200 myself, but I've discovered I have unusual mechanics even by two-finger standards--when I lock my arm for the backswing, it's not just bent, it's curved inward, so I get heavy side roll without much finger turn.
To this point, my success has been a result of years of practice, though it doesn't hurt that I usually target the most forgiving part of the lane using the most forgiving equipment. Right now I'm trying to add speed and smooth out my mechanics, figuring I'll be able to make up for lost hook by switching to more modern equipment.