It will all come with time. There is a 'click' around six months and you will feel better. Hang in there!
In the meanwhile, make yourself a good assignment sheet. Mine is blocked out by hours, so before I start, I fill in each patient's hourly stuff to do thruout the whole shift. (VS/assessments, meds, etc). Then I cross them out as I go. Yes there are always interruptions but at least its a framework and helps you remember things. I chart notes asap. Call a doctor, write a note. Get a weird finding or pt complaint, write the note. Takes a few minutes and saves many at the end of the shift. Check charts beginning, middle, and end of shift, sooner if expecting new orders. Group reasons to call the doctor so that its fewer phone calls. Enlist help from techs as much as you can--ambulating, emptying foleys, getting water/snacks for pts, changing beds...I do whatever of that stuff I can but I do ask for help when I need it.
I didn't get this system really down til about 5-6 months in, but I can tell you...I always get a dinner break, and I have never left more than 15 minutes late (unless I stayed longer on purpose). Stay positive! You can do this!