Is my new 8 month old boy part Maine Coon?

[chedesu]

He's turning 8 months end of this month I believe. Got him from these random people on a local ad that were getting evicted because they weren't allowed cats (Ugh).
They posted him as a maine coon but his head is supper tabby like so they said he's a mix. I have no idea now and had to take him to vet to get work done since I had no idea if they had ever given him a checkup or shots!
He's a healthy happy boy though, and very self assured. Took him all of 5 minutes in our place to get comfortable and friendly.
What do you guys think? He's almost 12 Lbs now but he could stand to lose a tiny bit says vet.