大学に進学しようと思うって英語でなんて言うの？

contemplating: to think deeply about

If you have been contemplating going to university it means that you consider applying to a school soon.

"I'd like to get into university soon so I can further my education and find a better job."

All of the above sentences can be used to describe what we are thinking about doing.at some point in the future, such as going to university.
Pondering means - to think carefully about something, especially for a noticeable length of time.

You are a working adult, and are thinking about going to college/university. You want to explain that. Any of the above suggestions would be adequate for this context.

1. I'm considering studying part-time to further my career.
   To consider shows intent and interest.To study part-time
   automatically means that you are working full-time.
   To further your career means to study or do additional
   courses that will help to improve your skills.

   2. I'd like to further my education on a part-time basis.
      Furthering your education means completing or adding on
      a degree/diploma course in order to move up in the company
      or to be considered for a promotion.

I might go to college - is a way to say that you're not really sure if you're going or not. So you're not 100% sure.

I am thinking of going to college - is similar to might, but you're considering it more.

I am considering going to college - Is similar to thinking about going to college

When you are a working person thinking about going to college/university to study (full-time); then you may explain this in the following ways:
-I am thinking about going to university
-I am considering going to college/university to study full-time.

Most working adults who pursue degrees do so on a part-time basis. Therefore you will mostly likely have to study part-time if you want to retain your job.
Here are some ways you can express this:-

1. I'm thinking of going to college/university part-time.
   As a part-time student you can attend class on evenings and/or Saturdays.

2. I'm thinking about studying for a Bachelor's / Master's degree.

Your example can be used but I put one more option just to be aware of other possibilities. Uni is a short from university. Considering has very close meaning to thinking that's why I used it in the second sentence.