Investing $900 per month makes such a gigantic difference for anyone who doesn’t have an unlimited budget. That’s $10800 per year even before counting interest.
A shared flat is no dream situation, but this sounds like a potentially life changing difference.
Also finding it through contracts is a good sign.
If it’s not 100% cozy, remember you could spend $500 per month making it cozier and you’d still be in the green.
Good luck!