Cortisol test and caffiene

Last month I had a cortisol test which came back normal but I'm still experiencing the same symptoms. On the day of the cortisol test, I drank coffee beforehand as they said it was okay to eat and drink before the test but now I'm thinking that the coffee could've affected the results as caffeine increases cortisol. The past 2 weeks I've been avoiding coffee.

Is it worth requesting another test?

I'm afraid that I might waste their time.

Im confused they do not have any valid test at all to determine an anxiety/panic disorder. Caffiene effects people differently anyway. What exactly was this test suppose to be indicative of?

The test was to measure my cortisol as I believed my cortisol levels were causing the anxiety. But I'm worried that the caffeine I had in the morning could've affected the results - which came back normal. So I'm really wondering if this is possible and whether I should ask to get retested for accurate results?

Hope that makes more sense