Please help with flash exposure

Hello everyone,

I took this picture of my daughter playing with a pair of old glasses. The picture was taken inside using my SB-700 flash. I think the picture looks ok but according to the histogram I would say it is underexposed.

What do you think? Is it ok or what can I do to improve?

My settings:
D700 in manual mode with 1/125 s, f/5.6 and ISO 400.
The flash was bounced backwards.

I would also like to add that I have only had this camera for 2 weeks, sold my D7000 and bought a D700.

Thanks

Greger