It looks to me that you're making a very common mistake, and indulging in what I call parrot learning.

What I mean by that is:

A parrot that learns to "speak" just imitates the noises that it hears. It learns to copy phonetically, but it doesn't really understand what it's saying, or the rules and structure of the language.

Likewise, it seems as though you are attempting to copy Loomis' diagrams line for line, imitating the shapes that you see, rather than getting to grips with the structures that they represent.

The real test of whether you understand the "language" is how you use it to create your own works.

I agree wtih EM

Buy the Jack Hamm figure book (under $10 bucks American) don't be fooled by the dated looks of the faces or figures  he was drawing his time.

also look up Kevin Chen he has posted all of his class demos on various sites

study proper proportions , learn anatomy and most importanly the planes of the body and head

Practice Practice Practice

at the least 3 hours a day on just the figure

Im with the others on that, draw all the time, from life, photos, on the bus, in the park... what ever and when ever you can, there is no substitution for it. 

draw a person, full figure, post that and I might be able to give you some tips, maybe, maybe not ;)

best opf luck either way

steve