Welcome Micah!
You can only control what you can control. You can't control your height. Dont worry about your size. My S graduated HS at that size. But, you need to get into the best physical condition possible to maximize your chances. And you can control your skill level - by working harder than everyone else.
The not playing on Shabbat will block you from D1s. Even assuming you have the necessary skills, not only will you miss Friday night games, you would miss all daytime Saturday games, and Sunday away games (the team travels either Thursday or early Friday and doesn't return until Sunday night). Because D1 rosters are capped, there is no room for a player not available for the majority of games.
D3s may be more flexible. But, only a coach can tell you his position. Moreover, coaches come and coaches go, so even if you find a coach who understands and allows a PT player, who knows if his successor would feel the same way.
Years ago, Maryland recuited an Orthodox basketball player; I recall other players mentioned in papers from time to time. Perhaps Google them and see how their schools resolved the issue.
Additionally, while inconceivable today, your views about Shabbat playing may evolve.
The only thing you can do now is work, work, work; improve, improve, improve (in class and on the field). Get your skills where you are recruitable, then worry about the rest of the puzzle.