Alloregnanolone is not made from DHT, it’s made from DHP.
You are probably thinking of androstanediol, which is formed by further reduction of DHT by 3a-HSD enzymes.
To answer your question, it doesn’t make sense, but low allopregnanolone is exactly what has been found in PFS patients.
About the sexual symptoms, it’s almost as if something that detects testosterone and DHT, 2 important male sexual hormones that still serve a function in regulating sexuality in women, and sends some sort of signal as a response to detecting those homones, isn’t functioning correcly.