The scale tells the tale

So, I finished the sleeves for the Outback Hoodie last night. I impatiently rushed to the scale to find out what the numbers may tell. I started with three 200 gm balls. So, about 21 oz total. Here is what happened:

Back 5.25 oz
Sleeves 6.25 oz
Total Used: 11.50 oz

Yarn Remaining: 9.5 oz

Now, for the kicker. I put everything on the scale together (the knit parts as well as the yet to be knitted yarn) and only got 19.5 oz. That is kind of a problem. That leaves only 8 oz to do the front and hood. The Front should, at very maximum, weigh as much as the back. So, that leaves 2.75 oz for the hood and the ribbing. Logic (sometimes fuzzy) tells me the hood probably weighs as much as a sleeve. So, I'm in trouble. That leaves nothing for ribbing.

If I did have the full 21 oz I think I'd be ok. I may just trudge ahead and knit the front, then see what is left for the hood and ribbing. I haven't frogged or have any small chunks of yarn laying around, so that missing few ounces must just be skein weight differential. I'm hoping that maybe I can squeek by with enough yarn, but my hopes are low at this point......