Pive aggressive co worker?

Im 1/2 way thru my training at a job in a Dr's office. Im still learning front desk procedures with insurance, etc. My trainer is a woman thats been there forever that seems almost scared of the Dr, is OCD and a control freak. She will show me the steps to complete a task but will leave out the most important piece of information that I need to get it finished and be able to do the task again. Shes very condescending to me and I would like to address it with her but do not want to start anything because she still needs to teach me some things that would affect whether Ill make it thru training or get the boot. I dont want there to be icky feelings but she talks to me like Im her child sometimes and gets very snippy when I least expect it. She seems threatened that the Dr and I get along very well and that the patients like me a lot. I need this job to support my family while my husband is in school. What can I do??? The Dr knows a little about this but I dont want to go running to him everytime I need advice on how to handle her. She also hints about things a lot though Ive asked her to be direct with me b/c Im not the type to get my feelings hurt easily-I want it all out there on the table. She is super sensitive and gets paranoid when she isnt involved in a conversation the Dr and I are having. Help!!! Im usually very good at these things but this has me stumped!