If you love the game you'll do what you can to get better. As mentioned before it's a lot of work. Are you spending hours daily year round on improving your game, getting stronger and faster? Do you love the grind more than the actual game because that's what college baseball is. It's a job...without pay. Have you gotten other opinions of your level of play besides from your HS coach? Being smaller than average certainly can be a set back, but if you are just as fast and strong it's not something that should hold you back. I would definitely recommend being evaluated by someone that is not bias. Problem is that's sometimes hard to find because as soon as you pay someone that opinion may end up being bias. You've got to be getting reps at practice. Are you performing at the same level as the starters? Do other teammates that are starters ever question why you aren't getting more play time?