Sorry Aubie is having this issue. It is not recommended that you feed a homemade diet to a dog unless you have it balanced nutritionally by a veterinary nutritionist. You will be causing vitamin and mineral deficiencies. Low magnesium can be the cause of the GI tract slowing down. Here is a website you can refer to if you want to make a homemade diet:
https://secure.balanceit.com/If you want to stick with feeding a softer food and do not want to continue the homemade diet then I suggest you buy canned dog food instead as it is nutritionally balanced for dogs.
If hard food seems to hurt her to chew she may have an issue with her teeth or mouth that needs to be addressed by your vet. A 6 year old dog should not have problems chewing hard dog food.
To resolve the current constipation issue I would recommend you feed her some canned pumpkin (pure pumpkin, not pie filling) ~1/4 cup twice a day. Feed it right out of the can. Do not mix it with her regular food. And you should also get a probiotic like Fortiflora and feed that to her for at least 2 weeks:
https://www.chewy.com/purina-pro-plan-veterinary-diets/dp/50029All of that being said, I strongly recommend you have her spayed if she is mix breed and you are not breeding her. Problems with her uterus can cause issues with the colon - if it is enlarged or has a tumor in it, that can push up on the colon making it hard to defecate. Also hormones can contribute to this issue.
Hope this helps. Best wishes.