In terms of the skills used, I would say you have used them correctly. You are looking at the chance of finding something through analysis, using you skill and understanding of medical knowledge. Perhaps though it should have been against Xenobiology as medical could be more about treatment of injuries or infections. There is potentially some overlap though, so don’t worry too much about it.
As converting your level of expertise to the chart, a training level of Expert converts to an acting rating of High on the chart, so you have converted it correctly.