Shallow mattress recommendations for front and side sleeper

Which mattress would you recommend for an average weight restless front and/or side sleeper? I don't like sinking deep into a mattress as I do toss and turn.
I have a 1.5 m high loft bed with maximum permitted mattress depth of 20 cm.
I currently have a 14 cm firm memory foam, which I now find a fraction too hard (it's 8 years old now), and would like something with a bit more bounce. I don't know if medium would be a step too far, or if medium firm would be better.
I've seen a couple of possibilities on your site, but would appreciate an expert opinion, based on your knowledge of the products.
Many thanks.