Your apprehension is normal. Shedding with Propecia (Finasteride), though it happens, is something we'd all like to avoid if possible. I suspect that you're correct, you've started a bit of a shed.
You may or may not know that "shedding", as is often referred to from Propecia use, is merely many hairs going into the telogen or "resting" phase all at the same time. All hair goes into the telogen phase, it's just that normally only 10% or so is in this phase at one time. During a Propecia shed........you may have more like 20%-30% of your hair that has been kicked into the telogen phase from starting on Propecia so you haven't "lost" the hair, it's just away on vacation and will come back soon! Make sense?? The Telogen phase lasts around 6 weeks then the hair starts coming back.........hopefully stronger and thicker..less inhibited by the DHT, right??
As for regrowth, if you experience any, it's impossible to predict. I've now been on Propecia (actually Proscar quartered) for almost 1 year and have noticed slight regrowth in the hairline, no doubt about it. I think it started around 6 months if I remember correctly. It's really not that cosmetically significant though it does soften my hairline somewhat. If I were you, I'd really commit to 1 year before reconvening the jury for the decision!! And, the best way to judge your progress is by documenting with pictures which i highly recommend you do if you haven't already........on a monthly basis from the same angles.