Yeah as Mitchibo mentioned most sources don't have any native rear channel content to make the 7.1 really useful and most tracks are only 5.1. Depending on the sound mode setting you have your AVR on it will sometimes up mix the 5.1 to 7.1 in some way.
I've updated my Dolby Atmos Height Guide with most of those new measurements and changed everything to Feet.
https://docs.google.com/spreadsheets/d/16PDbOdceFWBZ0zu7nsk5qFOzJofbo3440n6elHJ7w2U
But Some I've had to guess. Your stated ear height is a bit higher than average but you may be tall or have a high sofa. The height you give for your front speakers is a bit low and looks to be the height of the woofer but always look for the tweeter location when measuring speakers as our ears locate things based on higher frequencies much easier.
If you look at the "Listener Level Speakers" tab on my google doc you will find my estimation of your speakers angles. Your fronts seem to be a bit close together at 18.5 degrees to each side instead of the recommended range of 22-30 degrees. This is only an estimation based on a distance of 6 feet between speakers tweeters but you didn't supply this measurement. Getting the speakers wider may give you better sound tracking across your front sound stage which is the most important part and changing this doesn't cost you anything. Also think about your listening position distance as it is possible to move your Sofa Forward if you want which gives you a Bigger TV screen and more left/right separation on your front speakers.
If you want to go with Atmos height speakers you have three options as I mentioned earlier.
1. Front height/presence are small speakers mounted up at the top of the front wall set slightly wider than your front speakers. But you want a good vertical angle to them (ideally 45 degrees) for atmos height content to work well (the will work for Yamaha DSP presence use at lower angles fine though). Because you are so far back and with a low ceiling height this is not going to be easy for your room unless you move forward. You can ceiling mount these speakers instead of front wall mounting them using mounts like William linked to earlier but Dolby do not recommend bringing them out too far forward into the room like you may need to do.
2. Top front in ceiling speakers could mount up above you at the ideal 45 degrees position. Your type of ceiling with what look like ceiling tiles may effect things and it may be easy to mount them in these tiles but the surface they mount into should ideally be solid to avoid sound quality issues and I don't know if your ceiling tiles are. And if your ear height is really as high as you say it is then the speakers may be just too close to you which can make the sound too easy to locate to the speaker when you want your atmos height sound to not be too easy to locate.
3. Atmos enabled bouncy speakers or modules which may also be limited by your low ceiling height and some people like them and others think they are a stupid idea.
Look at the "Height Position Guide" Tab of the above Google Doc for some guidance on positions for these speakers.
Another thing to note if you wanted to go with Atmos is that with 5.1 you used to put the surround speakers about 2 feet above ear height but with Atmos setups you don't really want this as it reduces the ability for your system to output height and ear level signals as your whole rear is so elevated. They changed the recommendation to ear level instead. Also their recommendation for angles for rear surround speakers (which you can support as well as 2 height speakers with your AVR) is for angles of around +/-150 degrees which is like 30 degrees to either side behind you. For your room this puts them on your side walls about 18.5 feet from the front wall. We often think of rear surrounds as being almost directly behind you but this doesn't have to be the case it seems.
