The dentist probably recommended the soft brush because you're scrubbing your gums away. At least, that's why I've been told to get a soft brush/stop scrubbing so hard. You definitely don't need to be brushing 4 times a day -- start flossing instead and go back to 2 brushings like a normal person. Healthy gums are at least as important as the teeth themselves, since they hold the teeth in.
Interesting form of OCD minus the interesting part. And please, do tell us about about how you have to touch the light switch 12 times upon entering and leaving each room.
Those brushes are still covered with bacteria, millions of them, even after drying and microwaving. Buy four new toothbrushes every day, and soak each one in gin for an hour before you brush. Then give the leftover gin to the rats.
If it was invented in any other state, it would be called a TEETHbrush.