8" joists, 15' span

[Katharine Chartrand]

I am putting an addition on an old house that has 8" floor joists. For various reasons, it's very problematic to change the ceiling height between the original house and the addition. However, the smallest engineered floor joist I can find is 9 1/2". 

Code allows me to span 15'7" with 2x8" on 12" center. That's currently the only option I have, however, I've been told my floor will be bouncy.'' Is there anything else I should be considering?