Would it look sketchy that I didn't choose this prof to write me a rec?

So essentially, my current lac does not offer many courses in a field that I decided I wanted to major in. One of my courses last semester, the only thing directly related to said field I want to major in, was a really high level course that I had to talk to the professor a lot about to waiver into. I was the only freshman, and it was the only class I took where my writing improved. I don’t think I was anywhere near the smartest kid in the class, but I worked my butt off and got an A-. Later, I ended up as a research intern for a project he is planning on publishing in this field. I listed it as an activity in the common app, and I think I specifically mentioned this was for the prof who taught that high level class.

I ended up not asking him for a rec because I didn’t have the heart to tell him I was thinking of leaving, especially after my other profs ended up trying to talk me out transferring. I only applied to reaches, so it may very well be that I won’t get accepted anywhere and end up staying here any who. But considering he taught the only class I took first semester that was directly related to my intended major, will it seem suspicious that I did not choose him for a rec? My other profs who I asked for recs knew me very well…

Letters of recommendation are best when they come from professors that know you well, even if those professors do not teach in the area of your major.

That’s true. I’m just worried because it seems like my app would imply he knows me very well (i.e. the research)

Unless you still have time to get an LOR from this person, it is time for you to stop worrying about the decision that you made.

If you do have time for a letter, the best way to approach it is to tell the professor that you really liked the class, you like the research, and that you’d like to apply for transfer now so that you can have a chance to study that field in greater depth as an undergrad, rather than waiting until grad school. Chances are your prof will be sad about the thought of losing you, but also supportive of you pursuing a better opportunity in the specific field of study.