Learned a lot about toto toilets on this forum (and ended up buying a toto with a heart shape in the enamel on the back, which I think was a shout out to terry love)... so I thought I would ask about my shower problem.

Basically, the shower has very little water pressure and makes it extremely annoying to shower. Everything else in our condo has great water pressure so I think it has something to do with the valve. It's a modern shower head, so I assume that replacing the shower head with another low flow head wont do me much good, or do I have that wrong?

Here is a picture of the valve:

It is hard to turn off the water to do repairs here, so I am probably going to have to call out a plumber but I don't even know what work I need to have done.

Can anyone tell me what the possible problems might be and what type of valve I have?

Any help would be greatly appreciated. It's very frustrating!