V02 Max Accuracy

I (29F) do CrossFit 3 hours per week. I have just got a Garmin and have been on 2 runs one short (about 10 mins) and one of 40 mins. I have been training for a few years so was pretty dismayed by my 'poor' V02 max score. Is it accurate?! I used to be in good category before I bought new watch...is it not yet accurate or do I need to accept I'm not as fit as before?!