Yeah, finasteride can backfire on some people. This probably happens because hair follicle receptors can become more sensitive to DHT to compensate for the low DHT environment created by finasteride ( AR upregulation) I'm guessing that since everyone has a different sensitivity to DHT so the ones who benefit the most are the high DHT, lower sensitivity types. If you are losing hair with low DHT and the hair follicles adapt, I think the body overshoots the mark sometimes resulting in accelerated hairloss. It completely destroyed my hair in every way, lost a ton of hair in places that were still thick, including in the safe zones, and all of my hair became very fine. Unfortunately, finasteride can be a baldness pill for some. Not saying this is your reaction, but it could be. This must be rare or there would have have been an uproar about this by now.
Look at a few shed hairs and see if they taper towards the root. My hairs started doing this after I started finasteride.
I would absolutely NOT up the dose to 1 mg. Outside of that It's hard to give any recommendations. I will say that when I tried to taper off finasteride last year, I took about three weeks to go from .5 mg to .25 mg and after just one week on .25 mg, I lost 60%+ of my hair overnight and in the following days the remaining hair shafts thinned to a fraction of what they were just a week prior. My hair was literally melting. Very scary. I wouldn't have believed it if it didn't happen to me. Also, the hair in my nape area just vanished. A year later, nothing has grown back and things are looking really bad right now. I'm still on .5 mg.
I recently met a guy that started taking propecia in his mid fifties and he took it for about ten years and he said after he quit he started developing alopecia areata type bald patches all over his head, donor area and sides included.
So be careful if you decide to quit this drug, taper off very slowly, like many months, because it has the ability to turn hair that is DHT resistant into hair that is extremely sensitive to DHT and when your DHT levels return to normal they can overload the more sensitive receptors. Not good. There are a few forum members that have had this reaction.