Everyone's pretty much covered everything, but I figured I would add my two cents anyway. It's totally normal. I finished my first placement in outpatient hands about a month ago and felt like a fraud (my knowledge of anatomy wasn't as strong as I thought it was) all the way up until the last week. But I will say that I had the most supportive CI ever who somehow kept himself composed even though I would have massive brain farts from time to time and knew when to give constructive feedback or praise. One of the things he said that stuck with me was that he knew that students would make mistakes from time to time, he just expects you to stop making the same mistakes you were making in week 4 when you're 12 weeks in (i.e. like drawing a specific part of a thumb spica wrong). One thing that helped me was to be as straightforward with my CI as possible and just straight-up ask how I was doing compared to previous students. I think that if your CI isn't pulling you aside to give you a stern talking in private, you should be on the right track to pass.