In your photo your scarring looks to be more moderate than severe, in my opinion. I can't comment on subcision and fillers as I have not had these treatments myself but have you considered the eDermastamp at all? Your scars seem quite isolated so maybe this treatment would suit you also.
the thing about dermastamp is it will hit un scarred skin which i dont want.
Why? It won't damage your unscarred skin. Subcision will still effect your unscarred skin as the needle is inserted outside your scars, so into unscarred skin. Subcision will also cause bruising and possibly blood pooling under your skin (all good things) that will spread beyond the bounds of your scarring.
Skin needling is performed on unscarred skin anyway, for collagen production and product penetration so there are no risks of damaging your "normal" skin.