Ha! That's great man, even if it was done a while ago, it's fun to go through. If you get back into doing it, I'd love to see more!
Regarding ideas when drawing on paper... I'm actually the opposite, when doodling on paper I'm not sure what to go for, and when I start I can't correct it, so I kinda leave it behind, but on digital, I can look up references and adjust the image as needed, so I enjoy it more.
I think it's just about whatever you feel more comfortable with and to practice stuff to get "inspiration", for example:
1. Keep an idea notebook. Ideas come at the craziest times.
2. Do a low effort creative task, like doodling a thumbnail, or trying to write a simple back story for your image.
3. Create a routine. Marc mentioned something similar to set some time a day for creative work. It doesn't have to be too intensive, just 10 minutes to brainstorm is more than enough.
4. Learn something new. It can be as simple as watching a show, or researching about a theme than you are passionate about, like, history of comic art.
5. Appreciate other's work. Personally, I've found I've recieved a lot of ideas and learning lessons from feedback and just from watching other people's art journeys here.
There's a lot more, but just practicing some points to get the creative juices flowing is bound to help.