Tip: When working with the RD, do not turn the bike upside down. The RD won't work properly (gravity is going against it).

As to your chain's length - it looks fine to me (I still think you should do that right side up). I assume it's on the big-big combo? As per Park Tool's guide, there should be an S-bend at the jockey wheels for a properly-sized chain.

See Park Tool Co. » ParkTool Blog » Chain Length Sizing