After looking at your Tumblr, I think there could be lots of improvement.
First, how did he survive that? And why? How did the mane six end up with him, and why would they want to?
If it’s the end of time, of everything, then there is no wasteland. There is nothing, so you need a good reason for the TARDIS and those ponies to be there.
Where is the Doctor, and how did they get his TARDIS?
What is sign like? His interests, what his job was before everything ended, did he have family?
What made everything go away?
Just some questions. If you get those figured out, you’ll have a pretty good story. Could also help if you drew more.