Congrats on the twins, in all honesty you don't need an SUV. When I had my first I only drove a Polo and we managed, a friend of mine has three kids and they drive a Sandero.
Your Q5 is fine, my experience and theirs was similar to Saurons, you will probably more than likely never use the pram (I think we used ours twice), shopping for groceries while they are young, do it weekly and by yourself or your wife, trust me you do not want to take kids shopping.
I'm still trying to get this fascination with SUVs on suddenly becoming family cars, a station wagon or an MPV would be far better and safer, but somehow or other SUV became it. They don't offer that much space in reality over a normal sedan and when they do it requires the seats to go down, which defeats the purpose of having more seats, the Santa fe 7 seater has 515 liters of boot space, the Chevrolet Cruze has 450, so the higher insurance premiums, the more fuel, less comfortable and harder to park, sure you get a bit more cabin space but yeah cost vs practicality. Yet somehow the SUV wins.
Oh and taking a look your Q5 has a bigger boot then most SUVs??