"There is little milk in the refrigerator."
Translation:Hay poca leche en la nevera.
Principally you are right but as far as I know when you say "a little ..." it is more common to say.. "un poco de ...." regardless of the gender. Such as "un poco de leche" = "a little milk" or "un poco de cerveza" = "a little beer", even though both "leche" and "cerveza" are feminine.
la nevera and el refrigerador are 2 choices, thus both should be acceptable.
La refrigeradora is accepted but not el refrigerador. Must be a regional thing like computador and computadora.
Well, leche is feminine, so it would need to be pequeña and with a tilde. However, pequeño/a means "small," "little," so you wrote "there is small milk," which might work if one were complaining about the size of the carton/jug. Necesitamos una leche grande! So you want "Hay poca leche..." or "Hay un poco de leche..." The way you did the prepositional phrase was correct. Getting used to poco/a and pequeño/a and a feel for them in sentences takes time. Be patient.
I did "Hay un poco de leche en el refrigerador" and it was fine (July 17, 2019). Looking at some of these comments: the distinction between nevera and refrigerador is regional Spanish. There is discussion of terminology and slang here: https://forum.duolingo.com/comment/494351/El-refrigerador