I have not been in contact with my professors from school for a long time. Do I need letters of recommendation from my professors? I can get letters of recommendation from previous bosses at work and physicians I've worked with for sure.
If you plan on applying this cycle, you can't afford to keep waiting. Many schools have a preference for one letter from a science professor who taught you directly, one letter from a non-science professor, and then one additional letter of your choice. Some schools will expect a letter from a PI if you've been involved in research. I applied with 4 letters (biochemistry professor, social psychology professor, physiology professor, and neuroscience professor). I
asked well over 12 people, and actually received ~8 letters. (...and that's a good conversion rate in my opinion)
Expect having to ask many more people than the 3 writers you "need." People will say no outright; others will agree and ghost you; others still will agree and then require you to be after them begging and pleading via e-mail on a weekly basis until they write it. You may even have people who tell
you to write it. In general: treat a "yes" as a "maybe." You don't actually have a letter until it's sitting in your dossier. I recommend using a service like Interfolio to store and quality-check your letters for signatures and letterheads and whatnot.
Eventually you will get to a point where you have to do some critical thinking even after you get your letters. Not every person you ask will know you well. Depending on how excited they seemed to support you, you will have inklings around who
could actually write you a strong letter.
Further, you have to ask yourself how removed some of your writers could be from academia. There are some physicians who are also clinical professors and understand what a recommendation for medical school admissions looks like, but there are a lot more community physicians that will write a letter that reads like a work excuse for a patient. Worse, you could occasionally get someone who believes a recommendation letter is a place for them to air out any grievances they have about you or your work, which is functionally a kiss of death. You have to be careful... this is why I prefer professors to professionals.
I would also recommend seeing if your school offers a committee letter through the pre-health office at your old stomping grounds. For someone like you that does not have any letters, it could be a more "on-rails" experience, but a couple years out of school, I don't know if they will be willing to work with you. Worth a shot.
All of this to say, it's actually not an easy-breezy passerby thing to get letters. You want to ask people who recognize your face, who have spoken to you and know what you want to do, who have been present to see you participate fully in class or lab. I'm worried for you if you are concerned about who will write your letters in mid-February given that the theoretical list of people who could meet this list of requirements is generally slim especially for a non-trad.
Myself, I had to go back to school and take some additional upper-division coursework before applying. There was no other way for me to get letters I could trust. Several of my letter writers became writers because they asked me for recommendations (to add to their applications for tenure) first and were willing to return the favor. That was a very convenient aspect I didn't expect going in.