Have you taken both the ACT and the SAT? What kind of time are you putting into preparing for the tests when they are available? I would sign up for as many test dates as I could this fall, and I would put some real time into studying, and when I say study, that doesn't mean just reading over test questions. Put yourself in practice test mode and take timed tests that mimic the test setting. Then go back and look at each question you missed and find out why. The Army puts out a great program called March2Success and Khan Academy will link to your SAT scores to help you practice your weakest areas. Kaplan puts out study material for ACT. Another idea is to find someone in your area that offers SAT/ACT prep sessions. Sometimes those can help you gain a few points just by attending and listening to strategies.
It might feel like you don't have time, but you really do. You just need to push really hard to bring those scores up. Use all your free time to study and make it happen.