new grad nurse- not ready?

I just graduated in May 2009 with my RN and got a job right away on a medical floor. i was thrilled to have found a job right away and was very excited to get started with my orientation..well i was given 4wks of orientation, where after two wks my preceptor had me take our entire pt load while she would meanwhile do some of our tasks without telling me (such as adding in orders for admits that need to be done....shouldn't i be doing that so i know how?!...as well as calling the doctor/pharmacy/family/etc..) at the time yeah it bothered me, but i didn't worry about it too much. well now that i've been on my own for almost two months i feel like i didn't learn everything i should have during my orientation!
there has been a few times the charge nurse has asked me if i've filled out a certain form for a pt or put in an order that we're suppose to automatically put in when we admit the pt to the floor....i felt like a complete idiot when i had to tell her i didn't know what form she was talking about and didn't know i was suppose to do it!
last week a nurse pulled me aside and, very rudely, told me i had missed three medications the day before. i was shocked!!!! i try soo hard to look over my MAR as much as i can throughout the day, but to be honest it seems like i'm sooo busy and running around so much that i dont have time to sit down at a computer and look at new orders every five minutes!!!

is there anything i can do to prevent this from happening again? or anything to help get used to the floor and some of the smaller random tasks that need to be done? i just feel like i still dont know anything...and my supervisor wouldn't let me take a longer orientation because the other nurses on the floor felt like i was ready! how the heck would they know if i was ready!!!! anyways...sorry this is kind of long just needed to vent a little bit!