I'd say pumping has increased your supply - that's more likely to be causing a reduction in fats in the milk she takes than any amount of dummy use - Unlikely she'll take a dummy when hungry, no milk comes out of it!
If you're worried about foremilk/hindmilk imbalance, you can do a few things:\
1. Massage breast at the chest wall (the outside, not near the areola) before a feed to loosen fats off the walls of the milk ducts.
2. Pump one breast before feeding LO, start her on that side then switch to the other side. That gives her the hindmilk more so off the first breast and she can quench her thirst with the second side.
Stuff to know about foremilk and hindmilk - have a read here:
http://kellymom.com/bf/got-milk/basics/foremilk-hindmilk/It is absolutely possible you're seeing a reduction in comfort suckling at the breast given she has the dummy - not a nutritional issue necessarily.
It is also possible she's getting plenty of calories by feeding for 5min, my DS did and if you're making as much milk as you say, its quite likely she's getting enough to fill her tummy, especially as she is able to go 3-3.5hr between feeds.
