Thank you. I actually managed to solve it myself. I don't know if you have heard about it but I found an awesome online tool called truetype2gfx https://rop.nl/truetype2gfx/
What it does is lets you choose a font either FreeSans, FreeSerif or FreeMono (you can also upload your own). Then you set the font size you want and then it automatically creates a .h adafruit gfx font file that you can then download and use with your library.