Had embryo transfer 10 days ago and took hpt it said pregnant is this a false positive?

Depends: My guess is it is probably not a false positive and so a very preliminary incautious congratulations. I will add one thing and that is if you got Ovidrel it is less likely to be a false positive. If you had HCG administered intramuscularly then it is possible but also very unlikely that it 10 days it would still be giving you a false positive. Perhaps you should call your doctor and getting early blood test.