Great advice from the prior posters. Relax, it is going to take time to adjust to any bike. I have precisely the same issue, and I rode 240 miles this week on my road bike. This afternoon I took the mountain bike or for an easy 10 mile ride. Guess what?

It felt WEIRD! A bike on which I've ridden 2,000 miles in the past 12 months, felt WEIRD!

Just ride.