I'm on the same boat. There is a Curt hitch on Amazon. One of the reviews for it said that it fit his '11 E90 328i xDrive (Exactly the same car as me). However, Amazon says its incompatible with my car. Because of that I haven't pulled the trigger on it yet.

This is the link for it:

https://www.amazon.com/CURT-11033-Trailer-4-Inch-Receiver/dp/B004IY5FZY/ref=sr_1_1?dchild=1&keywords=e90+tow+hitch&qid=1599853316&sr=8-1