You have received a lot of good suggestions. I to have a little space and have turned the dining area and part of my bedroom into art spaces for illness purposes.
If you want to go forward to another medium I personally would suggest the pen and ink courses. All you need is a set of ink pens, Matt has many suggestions and there are a variety of good quality waterproof pens.
Both of the pen and ink courses are really good. A question, have you gone through the graphite courses? 25 days to better drawings or one of the other drawing courses? You mentioned dabbling in graphite wanting to be a wannabe artist. I did the same thing.
Also, if you start with pen and ink, you can then go onto line and wash combining ink and watercolor since you mentioned those two.
If I had known that there was pen and ink, I would have gone that way first, but went with my childhood memories of pencil, colored pencils, and then acrylic painting, which I enjoy all of them still.
I have supplies stored in boxes in corners of my apartment, labeled by medium, in empty drawers from end tables, and under my bed or behind a chest of drawers. In small spaces we can become creative, and it can be fun.
Some of the other mediums, charcoal which doesn’t take up much space, and pastels are also good starting places, both oil and soft pastels, especially to learn to be explorative.
Also, if you have difficulty getting reference pictures like I do there is a great site of royalty free pictures, Pixabay.com and they are a good source of inspiration.
Like I said, I too live in a small space. I have enjoyed learning to use all types of mediums and papers, it is a never-ending journey of enjoyment with a bump here or there along the way. We all make our path.
Hope this is not to overwhelming, happy artistic journey,