I'm hardly an expert on that software, but I know Photoshop and InDesign pretty well, and a lot of the controls are similar, so I don't feel completely lost. I decided not to redraw the whole sweater in Illustrator. I wanted to see what it would look like if I took a photograph of the sweater and used it as a basis for the schematic. I also could have used my original sketch, but I think the photo looks better.
I pulled a flat photo of the sweater into Photoshop, turned most of the background completely white, and imported it into Illustrator. Then, I just drew the lines and ovals I needed to show the measurements and added a few numbers with the Text tool.
It looks pretty clear to me. Although, I should probably whittle away a little more at that background and add a measurement for the length of the sleeves. The arrowheads are also maybe a little too big?
P.S. - If you want to learn new-to-you software in a way that's fast and easy, I can't recommend Lynda.com highly enough.