Hello Lovesmommy and welcome.
You indeed have a challenging situation. You say that you cannot bring your mother in for the interview to get the disabled transportation. Yet you are taking time off regularly to get her to these appointments. I would imagine it would serve you to take this time and get her the transportation which would free you up in the future from all her appointments that require transportation. It's all how you look at it. Spending a little more time once to get so much more time to yourself for work is a blessing.
If you tell us where you live, we might be able to come up with more solutions. There are senior centers, church organizations etc with volunteers who might also give some time to your mother. In major cities, there is also access a ride... but it requires some time and effort to research the options. Don't give up... give us as much info as you can and hopefully we can suggest other avenues for you to research.