Trying to trim the base of a URL, getting stuck

I have a column on a board with Twitter URLs. I’d like to trim out “https://twitter.com/” and be left with just the user name after the last /.

Example:
Begin: https://twitter.com/mytwitter
End: mytwitter

Does anyone have a formula that does this? I can’t find a function that easily searches the string, removes it, leaves the rest.

My goal is to VLOOKUP app this information against a column in another board.

Any help would be a life saver- Thanks!