You say you really want to try, and that's it important to you. Those are the words that should help you make up your mind.

I will admit that I'm still on disability, so I can't yet claim any achievement like getting back to work or starting and then finishing a graduate degree program. I will say that I understand fear of failure, but remind myself that I WILL keep taking steps forward. There are so many quotes about taking chances:

"You never know until you try"
"Better to have tried and failed, then never tried at all"

And many more.

I do know that when I take the step out of the safety of disability I don't want to find myself in a lion's den. If there is a way that you can work on your PhD over a slightly longer period, consider doing it. If there is a way you can line up an extra support team, consider doing it. If you can find a way to ease up your other responsibilities in your life for more energy for your PhD program, then do it. Etc.

All the best!