Hmmm you sure you've counted well? My maths are different, and not in your favour
For this
double thrusts you should go after the dildo has spent some time in the freezer or in icy water. Then go for some
vibe time.
I also think you should edge a bit while doing all of this, to add to the torture. I'd say every 50 thrusts you should roll a d6:
1: nothing happens
2-3: reach one edge before you can continue
4-5: reach five edges before you can continue
6: reach ten edges before you can continue