Introduce Chastity/Masturbation Denial
Hopefully by now, your sub is starting to get the idea. Control that further by not allowing any masturbation or chastity if you feel the need. You should at this point be very in control of your sub. Start teasing them about how you’re going to finally get them off for being such a good sub. Remind them of this daily, add to your story daily, just give them small bits of info at a time. Watch you sub start to meltdown over the next few days