Home mortgage as rent

I live with my brother and owned that house until Sept 2020 we refinance and I no longer owner of the house (including deed/mortgage). I did pay 1/2 of mortgages for full year 2020. I have a 1099-MISC job, which is 100% work from home. Can I deduct 3 months as rent expense? or should I use home office deduction.  From what I see, home office deduction (250 sq. ft) is small and its only for home office. Since I work and live in the house & pay rent, which would be higher. Can I deduct rent/insurance/water bill