Don't get down if colleges aren't clamoring for you.
I attended a handful of showcases and threw very well. I was a tall lanky guy (think 6'3" 165 lbs) that topped out at 86, so I wasn't exactly standing out to anyone physically. I would leave showcases with great numbers in the scrimmages and tournament games, only to get no calls/letters from programs.
I kind of marketed myself to the schools that I applied to (one DI, one DII, two DIII). Once you apply the coaches are usually willing to hear you out, as that's a relatively low cost to recruit at that point. The school I ended up choosing did kind of start "recruiting" me once I was on their admissions radar. The assistant coach would call in the evenings and chat me up and things like that.
Unless you are a physical stud, which guys like you and me aren't, you are not going to get recruiting letters and VIP treatment from colleges you have not even expressed interest in. Accept this, and instead enter with the mindset that, just like everything in life, you are going to have to put in the work and have the patience to succeed.
I ended up setting school records in ERA and appearances, so don't think being heavily recruited = success or the opposite Good luck!