Try setting the width that the portal is allowed before the autoheight command - it'll probably be something simple like
Code:
portal[notes].width = width
lineheight is not a pixel-based number. It is the number of lines of text to allow within a text portal. So it's normally used in cases where you want to allow a maximum of 3 lines of text, and cut off anything else, or where you always want to show 2 lines, even if the text in this particular item would only require 1, because you want it to match with all the rest of the uses of this portal where it'll usually need 2 lines.