1. Play your senior year. This is a red flag to colleges if you don't. Colleges expect you to have the time to train with them, play with the team, workout on your own and handle multiple college courses. They will not accept the excuse that you didn't play with your high school team for 10 hours a week so you could train on your own.
2. While you are playing you can still train on your own and yes you should do that. (Gym membership, weight room at school, or if neither of those fit there are many inexpensive ways to train. I know of a boy who bought a dumb bell set at a garage sale and he tapes them around himself while he runs uphill in his neighborhood. He also rigged a shirt to hold them to his back while he does crunches. There are ways you can work out, and gain strength and speed, google it.)
3. Which do you want more, the college experience at a 4 year college or to continue to play baseball, you may have to choose. (You do know that MANY colleges have an intramural baseball program so while you won't be playing for the school you can still play baseball in college right?)
4. In my OPINION if you aren't a MiLB hopeful you should prioritize what school you want based on your academic needs rather than your baseball wants. If you are a MiLB hopeful then the JUCO route is likely your best shot to prove yourself.
5. The showcases you attend will be based on the type of school you want to go to.
A word of caution, if your goal is to PLAY at the next level be mindful that some teams may be more attracted to your GPA than your playing skills. There are MANY programs that will take a kid like yourself to assist their overall team GPA, but you won't see the field.