Look at the shadow line you have going down the nose. Yours is straight. She has two big inward dips. One between her eyes and another a bit farther down. That's important to her likeness. I wish I knew how to photoshop the line to show you. You have the line correct at the bottom of her nose(between the two nostrils) but I see much more highlight on the left side of it.
I can go with Martins suggestion. We each do our own set-up. As far as the 6 hr limit, I know right now I'll probably cheat on that one. If we do decide to do a still life challenge, here's a video I found to be very interesting. At mark 23:27 he shows how to light the display. I actually bought that lightings/tripod/barn door set. I just got it and tried it out today. It's fantastic. The barn door attachment is the best part. I also bought the dimmer attachment but wish I hadn't. I purchased through B & H. LTM Pepper 100w Fresnel Light, LTM 4-Leaf Barndoor FPepper 100w, Impact ESR Lamp (100w/120-130v)bulbs, and Impact 9.5' HD Air-Cushioned Light Stand-B.
This is turning out awesome! Make sure the shadow line running down your nose is exact. Even if it dips in a tweak can make a difference. Also, the shadow on the end of you nose. Make sure the shadow line is over to the left enough.
Congratulations on your first painting. I like the books! There may have been more value changes that should have been put in on them. That's so important. When we're first learning we don't always look close enough for them. I would also work on softening some lines and only sharpen the lines that you really want to put emphasis on. I look forward to seeing your next one.