Don't forget to add a 5 second bonus to your time controls.
This will teach you to reach the end of the game "on the board," instead of "on the clock." Endgame knowledge can (also) be implemented and played quickly.
Studying (intensely) both Tactics, and Endgames, will vault you into the higher ratings. Bullet will only improve your reflexes, and you're already young enough that you don't need that kind of help.
Openings are mostly a "black hole" for your study-time. Under USCF 1900, any mainline opening is pretty much as good as another. Learn only enough opening theory to get yourself a decent middlegame. That's all you'll need when starting out.
First order of business (for openings) is to determine what openings to play with the BLACK pieces against 1) e4, or 1) d4.
With the WHITE pieces, you can always just play reversed Black systems, like Larsen's Attack, which is a reversed Queen's Indian Defense (QID), from the white side. Simple.
Openings are largely a matter of personal taste. Choose what suits you.
Good Luck with It.
Sounds great. Thank you EliasAStern. :)