Reminds me of a peony although I could be wrong. But it will have a deep tap root if it is, fleshy stalks, fast growth from fat buds in early spring, flowers may-ish (mine did) and various small shrub sizes. Resent moving and need shallow planting to flower well.
Actually, this will sound crazy maybe, but what's its habit? Because it could pass for Clematis Montana if it climbs. The leaf colour and shape and that abundance of simple pinkish flowers on stems is strangely familiar. Also, its habit of growth from the centre of the stem reminds me of Clematis, perhaps its not a shrub at all?
I agree with Holedigger
Cut back as hard as you like after it has flowered. I have cut back right into a 2" thick main stem of one that had got way out of control, but that took two years get fully reestablished. To maintain the existing size and flowering you should cut back to the start of this year's growth. Next year's flowers will form on this year's new growth so if you leave pruning till summer the new growth will not have time to ripen fully.
My favourite clematis montana is Warwickshire, which produces bronzy purple leaves that contrast delightfully with the pink flowers. The leaves remain that colour right through the summer, which is a big bonus.
After it has flowered it puts on new growth. In July take semi ripe cuttings. they root very easily. Google for how to take clematis cuttings, but basically, imagine a letter T with the cross piece being a pair of leaves. The vertical is the stem below the leaves. Allow 3 " of stem, and on one side use a sharp blade (Stanley knife type) to skin the bottom 1/2" of one side of the stem to expose extra surface for the rooting compound. Cover and put them out of sunlight. They should root in eight weeks.