juskojj – have you gone through the Heart Rate Drift Test article on UA? It explains how to administer the test (outdoor/indoors), drift calculation and what you should use as your AeT.
In your case, your drift (144/137) is around 5.1%. If you want to set AeT based on this test, then your initial HR ~135 would be your AeT.
In terms of timeline to cure ADS (get AeT within 10% of AnT) the forum topic below might provide some insight.