"There is little milk in the refrigerator."
Translation:Hay poca leche en la nevera.
la nevera and el refrigerador are 2 choices, thus both should be acceptable.
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