Yes. This will be possible. This does not mean that you will be accepted to every possible small school, but there are a lot of them and you can get accepted to some very good ones (particularly given your excellent high school record and test scores).
Right now the main thing is to get well. Are you seeing a psychiatrist or psychologist to help you deal with depression? The medical community really has gotten a lot better at dealing with depression. Depression is common, and some people believe that it is more common among very smart people. When you get well, there will still be many great colleges and universities for you to choose from.
The next thing would be to figure out what type of school would be a good fit for you.
Since you have no university courses completed after graduating high school, and a valid medical withdrawal, I am not sure whether you are a transfer student. You might be looked at more like the way a student would be considered while taking a gap year. Admissions staff at any university that you are considering will know the answer to this.
Northwestern is a bit smaller than UC Berkeley. However it is not necessarily any less stressful. It is certainly a highly ranked and academically very demanding university. The quarter system seems to me like sort of a mixed blessing. When I was in graduate school I very much liked the quarter system. You get to take more courses during an academic year so that subjects you really like you take the next course in the sequence, but subjects that are not quite as important to you do not go on for quite as long and you get to take more of them. However, the end of the quarter comes up quickly and this works better if you are inclined to always stay ahead in classes. This will be a lot of work at any highly ranked university.
I suppose that you could apply to a range of universities now, then by sometime in April you can decide which if any you would like to start at in September of 2022. Life is not a race and taking a year or two to get ready and to plan the next step is a very reasonable thing to do.