Welcome. What they said. Full disclosure. I am Morpheus let me show how deep the rabbit hole goes.
Locally, we have the Stanford University human performance lab where they do VO2Max and lactate threshold testing either on their stationary bike or your own road bike in the lab with a mask on and blood samples taken and analyzed. And they will meet you on a local climb on the road and take blood samples as you do repeat climbs for 2X the price of the lab to calculate LT. And the woman who runs the lab used to be a member of our racing club and is an accomplished racer.
At one point in time, I thought about going to Stanford but the cost of the test is high and one can get a great indication of fitness by using a power meter and doing testing following a protocol. As ones fitness changes, field tests confirm changes to the training program. After a few tests, one has paid for a power meter.
Take the red pill and continue or take the blue pill and everything will be back to where you were before your post riding with the fast "boys and girls" and thinking you are fabulous.