How does finasteride work?

I know how it works chemically. I mean in practice. I’ve been on finasteride for 4.5 months now and haven’t noticed any regrowth and my hair is starting to shed quite a bit again. I obsess over this every day and it’s destroyed my confidence. My hair is about an inch long right now so i think it would be difficult to notice subtle regrowth anyway. Most of the hair fall I’ve been experiencing lately has been pretty short hairs. Maybe about a centimeter on average. I know finasteride takes time to strengthen miniaturized hair follicles but I guess my question is, is it common for hair to start growing back and then just fall right back out? I’m wondering if maybe it can take a couple of growth cycles for the hair to actually be strengthened enough to grow out and stay without falling. Anyone have any insight?

Hair cycling between growth and rest, is mediated by an enzyme called 5 Alpha-Reductase which is present in small amounts and converts testosterone to dihydrotestosterone (DHT). Testosterone affects lean body tissue, muscle size, muscle strength, and sexual function in men. In men who are genetically predisposed to develop androgenetic alopecia (AGA; male pattern hair loss), endogenous androgens alter scalp hair follicles, resulting in production of vellus-like, miniaturised hair, rather than cosmetically significant terminal (normal, full bodied) hair. This change leads to a progressive decline in visible scalp hair density, readily perceived by the patient as thinning and, eventually, baldness. The benefit to finasteride occur over from 6 months to 2 years.