I would guess if you are in NY that you probably do have an eastern...it is the garter most likely to be found on the east coast. From the pics...she looks like an eastern...but it is hard for me to get a really good look at her...if you could get some close up pics of the side of her face and her body...I could tell you for sure. From what I can see of her head...she does look like a T.s.sirtalis to me...and easterns often have some red in between the scales. If she is a female...she would be young though..otherwise she is a he...adult female easterns are usually quite larger...around 3 feet long. For a snake that size...I would start with worms...if she is an eastern, that is what she will be used to eating in the wild. Make sure they are earthworms or nightcrawlers. 1-2 every 5 days. You can also feed 1-2 pinkies every 5 days...you may want to cut them up. Or, you can feed fish fillet...I feed mine tilapia and trout, and occasionally salmon...always fresh from the seafood counter...raw...cut up into pieces...the equivalent of a pinky or two worth of food every 5 days. If she won't eat the pinkies right away...you can sent the pinkies with the worms...but you might want to consider feeding her a varied diet of pinkies, worms, and fish...that is what I like to feed my snakes.