In my experience, a reasonably tough priest can be hard to find. I don’t know where you live, but the local FSSP or the pastor of the local Latin Mass community may be a good place to start. Other than that, if is somewhere where multiple priests hear confessions regularly, look for the guy with the shortest line.
Beyond this, there’s always the option of talking to your regular confessor. Many priests seem averse to asking questions in the confessional. (I don’t know why. Fear of interrupting? Fear of seeming too judgemental or inquisitorial?) If your confessor knew you would like some additional direction, I’m sure he would oblige. There’s also the option of asking for a different penance. You could ask, for instance, if there’s any spiritual writer he knows of who would be helpful in your situation.
In Christ,
JAC