In TextEdit, check the menu File / Page Setup, and confirm that the paper size is set correctly, and that 'scale' is set to 100%.
If that's correct, the defaults (TextEdit / Preferences... / New Document / Font) should be the font size printed. Note existing documents may already have a larger font size set. Make sure you're viewing the document at the original size (View / Actual size, or Apple-0), set the font size as you want it, and check out the preview in the Print dialogue box.
Hope this helps!