Could I have repressed memories of therapy sessions for an eating disorder I had about 7 years ago? I can barely remember anything we did. I was 11.

Why would you? The human brain is blessed with the ability to selectively forget information or memories that have little or no value in present day use. Sometimes memories can be resurrected with triggers, but many don't hit the "memorable" category that would make this possible. If you need more work, seek out a therapist who can help. What helped an 11 yo likely needs to be modified for an adult.
Past psychotherapy. It's not unusual to forget some things that happened 7 years ago -- but why are you wondering about it now? Is your eating disorder still going on, or getting revived? It's not unusual to have that happen either. If you're concerned about your eating, or want a refresher in therapy, you can contact the therapist you saw previously -- or your physician can help you find a new one if needed.