For measuring the lactate threshold , would help to have someone, in order to be more accurate .
But measuring like you did, you can only see that as normal , lactate concentration in blood will increase with exercise if your work is done above zone 2 .
The lactate is produced in higher percentage when you work with higher intensities , the body has the capacity to remove it but in the aerobic zones where the percentage that the lactate produced is low and the body works mostly aerobic.
AeT is when you have 2 mmol and will correspond to heart rate at a certain pace , speed or power .
AnT 4 mmol …
Those values can change slightly in some athletes but in general those values are standard .
I hope I could answer all your questions