This may have been posted before because it looks so damn familiar but I didn't find anything when searching. Anyway I found a Japanese artist
website that dealt with
tentacles drawings, and upon further browsing, I stumbled upon a sample doujin that had some breast expansion in it. Haven't been able to find this doujin on share, so bare with this sample for now.
Here are some links to the doujin
Info from original website
DLsite.com site