It's up to you which rhetoric to use when choosing the size of a TV. Everyone's opinion of too big or too small is different.
If you are interested in seeing the biggest improvement in sheer detail when using good quality sources you should get the biggest TV you can fit in that space.
A guide to the best viewing distances when watching Full HD or Ultra HD 4K TVs.
www.avforums.com
Following the SMPTE guidelines means you'll never go above 30 degree angle each side of the TV. Just multiply the screen diagonal by 1.6.
But they sit on the most conservative side of how far you should view your TV, other organisations, and theoretics state you need to view a lot closer to benefit from increase detail.
Probably a 55" is fine at that viewing distance, but a 65" would be more suitable if you want to get the most detail from the picture, but then you start to tread in dangerous water with the edges being darker.