Hey @Rikako W. congrats! That sounds awesome.
I'd be cautious in Union City about the possibility of converting things (like 2 to 3 family or whatever) and I think a number of other Union City investors would be as well. The building department can be incredibly difficult to work with, and their records are shoddy, at best. In New Jersey, for 3 family buildings and up, both the state and the city are involved (the state does a multiple dwelling inspection every 5 years, the city maintains its own, not necessarily consistent, records of how many units a building has). I've been in the process of buying a house here for ~8 months, held up because the state of New Jersey believes it is a 3 family (and has inspected it as such... and, curiously, uses Union City's own inspectors to do this), while Union City believes it is a 2 family. It's functionally impossible to comply with both state and city laws simultaneously, so it's an absolute nightmare. There are many stories here on BP of of investors on BP that have encountered similar insanity. If Union City believes the building is a 3 family currently, you are in luck. If not, it will be a challenge (and not something that will likely happen before you close unless your seller is incredibly motivated and kind). Union City is also particularly sensitive about basement apartments: there was a program ~10+ years ago where many basement apartments were "legalized" to a third unit, but you'd likely not be able to get a certificate of occupancy today if you had to receive a new one because they don't comply with the current fire code (windows not large enough, no sprinkler system, etc.).
Those numbers look pretty good to me, but I always count vacancy. Even if people are knocking down the door to get into your place you will have some vacancy just to account for cleaning/maintenance etc. between tenants, and, if people really are breaking down your door, you're probably not charging enough for rent. There's no additional cost for garbage in UC, but there is a sewerage cost which is related to but separate from your water bill, and will be a few hundred dollars per quarter for the house. I provide water to tenants--I'd be OK providing water, heat, hot water, but never electricity (can be astronomically expensive particularly if they're not paying, or in the weird situation where they pay for gas heat but not electricity they'll bring in a bunch of space heaters).
There are some miscellaneous things that you may or may not account for if you're living there, like snow removal (could be expensive depending on the property, but maybe a few hundred dollars), cost of finding tenants (if you use a broker or an agent), miscellaneous accounting and/or legal fees.
You said there are 3 meters: are there 3 separate water heaters and furnaces? If not, then you'll either have to pay utilities for one unit (because that unit is paying for the heat and hot water) or have a separate gas meter installed for the central furnace and hot water heater. A lot of 3 unit buildings we have 4 meters: one for each unit, and then a common meter for things like common heating, outdoor lights if any, etc.
I think Union City is getting super heated, so it's hard to find quality returns, particularly in the 2-3 family range because you're competing with seasoned investors plus house hackers plus pretty much everyone who can afford a down payment. If you look deeper into Jersey City there are still deals, but you'll have to account for concerns with crime and lower quality tenants. You could also look into the Newark area but that has similar concerns as deeper into Jersey City.
Best of luck!