gdod going!!!

lesee you'll get use to the frame size, you want to have a lot of room to move your body around. I ride a 15" myself, I"m 5-3 and it's perfect for me

You may need to have your fork "tuned' if you are bouncing all over the place... it could also be a factor of learning to find your balance point on hills. typically in mountain biking you save standing hills for a technical uphill move, or for some extra momentum at the crest of a rise, passing someone, but not as a regular thing.