Did you take any SAT practice tests that might have indicated those scores were an outlier?
I got a 170 on the PSAT (obviously pretty average) and always thought of myself as a smart kid. I was pretty bummed. I then took the ACT and on my first try got a 29 (33 E, 26 M, 27 R, 31 S) and with little to no effort I am positive I can get that 29 above a 30 in June when I take the ACT again.
Take the ACT. See which one you like better. I’ll warn you though, the math on the practice ACT site versus the math on the real ACT is pretty different… the real test is harder. But nothing too daunting. 
Yup.
Know why?
- Overconfidence (and fall for generic SAT traps)
- Little Practice (b/c of self pride)
- SAT is counter intuitive (it's a standardized test)
Don’t worry though, I did the same thing. I took my first SAT cold because I was wayyyyyyy too overconfident. I bombed with a 1760. For me, such a low score motivated me to try harder and find some reason to do better. After finding out that people who smoke pot and partied all day did better than me, I went nuts and prepared for the SATs more than I have any other test. I took the test last Sunday and I have a good feeling that I’ve improved ~250 points.
For a tip, the SAT isn’t something that people ace on their first attempt blindfolded. Practice practice practice! (Get a blue book) There’s a certain way SAT has to ask certain types of questions, and once you get the hang of it, the test becomes easy.
Moreover, most prep classes are not useful unless you lack material that you should already know by now and have no motivation. Self discipline and self motivation works wonders for these kinds of tests.
Also if it’s the wording that throws you off, and you have no trouble with time, the ACTs may be a better option. It contains the same material, just slightly harder, but more straightforward. Time is everything though.
If you study with E. Meltzer’s prep books and McClenathan’s essay and math books, your score will go up on the SATs. Just discipline yourself and give yourself 3 chapters a week as hw. The SAT was not written by school teachers- it doesn’t reflect what they ask in school. These books are great at explaining the best approach to the questions. Good luck!