19 year old Investment Banking Experience

Am pursuing my undergrads in Finance from a tier 1 University in India .

I have previously worked at big 4 and some big corporations in India and a year long startup experience.

Lately , I shifted my focus to working in investment banking.

Obviously, as I am a college kid still in my undergrads ( sophomore ) and have to work part time, hence no elite bank was going to hire me excluding summer internships .

Hence I started working in a mid market boutique investment bank .

Here i execute deals all by myself along side the MD of the firm.
Be it MnA deals , Equity Fundraising or Debt syndication .
The exposure has been massive especially at my age.
Which I believe gives me an edge when I apply to a Goldman for my summer internship in the next 3-4 months.

But the work culture is really poor ,like the way the MD behaves is really bad and unprofessional like most of the interns don't even stay for 6 months and quit because of the behaviour.

Even though the exposure has been great , Should I stay in a firm like this , or look for somewhere else ?

Also how should I ideally prepare myself for a summer internship at an elite investment bank ?