Yeah, you chose a particulaly hard angle there hon ^^; I can't think of the last time I tried it myself, which is why my sketch wasn't too great, but find some photo referances, or get a friend or someone to try that angle on them selves. I sometimes get my brother to do that on the ones I can't find refs for ^^;
It was difficult! I found that out the hard way but your sketch cleared it up for me and I'll be able to fix it now. My brother wouldn't pose for me if his life depended on it so I have to wing it sometimes. Like this pic for instance