NATA

It's better if you can join during +2 vacations or holidays.
Now, for the time being, you better keep your focus on +1 and +2.

Yes, you can get admission in a good college for B.Arch. You just need to qualify JEE Mains paper 2 with good marks. You need to score a minimum of 75% in HSc too.

I think you should look for some private colleges in your region. Getting a govt. college with this score is really difficult.

Mahatma Education Society's Pillai's College of Architecture, New Panvel
Rizvi College of Architecture,Bandra(W), Mumbai
Rachna Sansad Academy of Architecture, Mumbai
Sir JJ College of Architecture, Mumbai
Late Shri. Vishnu Waman Thakur Charitable Trust, Viva Institute of Technology, Shirgaon