Where to start? Have multi on a large lot...want to develop

[S Yu]

Hey guys, wasn't sure where I would post this but I think this might be the best category. I own several properties, but this one I picked up in a Boston suburb a few years ago.

It's a 3 family unit - 2 separate houses, 1 SFH and a 2 family. They are located on the same plot of land.

The entire lot is ~ 11000 sqft and these two houses take up less than 1/3 of that, the rest of the property is just yard. I making $500-800 positive cashflow after all expenses, etc so it's a pretty nice.

How do I go about expanding? I don't even know who I should start to talk to. I want to see what my options are such as building something on the free plot of land... or tearing down the current two houses there and building a small apt complex of like 10-15 units or something. Should I talk to a general contractor? Engineer? the City? I need some direction as this is very new to me.

I really appreciate the help.