I'm seriously struggling with letters of recommendation.

I graduated from college 9 years ago and even though I had great relationships with many professors, I'm honestly really not sure how well they'll remember me after all this time and I haven't kept contact with them at all since I graduated.

I don't want to get letters from my current employer since that will inform them of my intent to leave. That leaves just my previous employer, and my supervisor there had a pretty spotty relationship with me. I'm really struggling to pull something together, can I use letters from non-supervisor coworkers at my previous place? I had a better relationship with them than my boss.

If not, I'm thinking I can either try setting up a call with an old professor to get back in touch and rejog their memory of things I accomplished in their class. Or I can give my current company a 12-month in advance notice that I'm planning to go back to school and hope that informing them a year out will keep things amicable. I really don't want to do this, but I do have a good relationship with several managers at my current place.