How do I know if my mom is in later stages of dementia?

My mom (74 years old) was diagnosed with dementia about 4 years ago. We saw signs of it before that but she was still living by herself at the time with some help from a caregiver twice a week. About 18 months ago things started to go downhill and it was very obvious to us that she could no longer live by herself. We moved her to our state to an assisted living nearby. She seemed to actually improve for a few months after moving here but in the last year she has seemed to be making a steady decline. Lately, she has slowly started to lose her appetite and doesn't want to go anywhere. I go see her 4 times a week and make sure she's eating something, bring her yogurt, bagels, peanut butter, etc. (The facility brings her room trays cause she refuses to go to the dining room) She has physical therapy come two days per week and I have Visiting nurses see her 2 times per week when I can't be there. I do it that way so that each day she has someone to check on her, clean up her apartment and take her for a walk. (The assisted living doesn't provide someone that would take her for a walk). She used to want to go outside but now says she's too nervous and rarely even walks for more than 15 minutes and then says she's too tired/weak/dizzy, etc. She seems to just want to sleep most of the time. She definitely still recognizes my family and I and some of her caregivers but doesn't remember most things, doesn't know what day it is, thinks she's still in Denver. She has a visiting physician that see's her twice per month. Hates to get in the car and go anywhere. Also, seems to be having increased delusions such as people are in living her apartment or my deceased father comes to see her at night. Just not sure if I should force her to go see the neurologist and put her through that if there isn't really anything he can do for her(?) For the most part she is calm and content, she just doesn't want to do much of anything. Just want to make sure I'm doing all that I'm supposed to be doing.