Mike @lolmypally I think you said it all in your second sentence - she's turning six so she's no longer the hyper young pup that most of us expect.
Ignoring the weather - it's a tad warm here today at about 90° (humidity must be up, it feels warmer) my three are all crashed. One on the floor under my chair, one in the middle of the living room and one in her corner on the (cooler?) tile.Since I'm not one of the active members of the community, my dogs don't get the exercise they really need but they're all content. Like in your second picture, two of my three are splayed out, belly up fashion and they wouldn't do that if they weren't really comfortable.
I have one who has free run outside because she stays close (within 100ft) to me; the other two are on leads when they go out and they play with each other when they aren't chasing cats (I have two of those too) so they get a bit of exercise.
The main thing I'm looking for is are they content as they are - and mine are and yours also looks satisfied to be with you ... long story short, don't sweat the small stuff unless you have real reasons to thinks she's unhappy.
What does your raw feeding look like? How much do you feed? Are you feeding 80-10-10? 80-10-5-5? How much of what kind of human food was she getting?
In general at 6 it's normal for some slowing down to happen. At 45 minutes to an hour of walking a day it wouldn't take much slowing down to think something was wrong since that might not be much walking depending on your pace. For the most part though at 6 is when they slow down and any arthritis they might have will start to show itself. With raw feeding you should have oily fish as part of your diet but if not add some fish oil and vitamin E. I noticed some slowing with my girl around 6. A shorter walk sated her at that age, but she should still be able to go out and put on the miles. Do you walk the same course every day or real close to the same course? Changing things up a bit, going somewhere new with new smells helps to put some pep back in the step of most.
Slowing down is natural but with raw feeding it is paramount that you are definitely feeding balanced meals. If you aren't balancing the meals properly it can affect their health and longevity. It can slow them down more than it normally would, cause bone density issues, age their internals faster, eventually lead to kidney and liver damage. Raw can be the best thing for a dog, or the worst thing if done improperly, which is why I was verifying. We can love them to death. Literally.
An older unspayed female has to be watched closely for Pyometra. It is a secondary infection that happens in the uterus due to an imbalance and build up of hormones that comes with being allowed to cycle but not have pups. The infection is hard to spot coming and if not caught it will kill the dog quickly. The older she gets the more at risk she will become to succumb to Pyometra. The only way to ensure this will never happen is spaying. Frankly, she will probably be much happier being spayed. Heat cycles are no joke and not that comfortable. While no one likes to be put under, the long term advantages outweigh it....for now. The older she is though the harder being put under will be on her, so I wouldn't put off getting her spayed much longer or you will have to weigh the risk of pyometra vs the risk of anesthesia.