Thanks for your comments. To address a few questions:
First, our practicum evals require supervisors to rate us on a number of domains. While I did receive "unsatisfactory" ratings in a few domains (relating to non-specific skills and areas like rapport), as far as I know, I didn't receive an "unsatisfactory" rating for the practicum as a whole.
I knew I had weaknesses in some areas and have been working to address them. Most of them have been mentioned before by other supervisors (although I've never received any "unsatisfactory" ratings before), and I honestly feel like I've been improving in those areas. However, the practicum was a supplemental prac to provide me with more therapy experience, and so I was only there one day a week and had a small caseload. Thus, I feel like my supervisor was working off a minimal amount of interaction when evaluating me. For example, she had concerns about my therapeutic alliance skills based on one client who dropped out of therapy, even though I've had success with long-term clients at other sites. Also, my eval at my main prac (which was almost all assessment) was pretty balanced. I was careful not be defensive about the negative eval.