3 weeks is much too short a timeframe to see any difference in your hairline, unless you are suffering from some sort of aggressive alopecia or are currently undergoing chemotherapy.
Things seem worse than before because you are obsessing about it. I'm guessing you examine your hairline daily? Finasteride takes minimum 3 months to start working, and that is if you are extremely lucky. Don't expect to see any changes before the first year. Forget about your hair for now, and hope to be pleasantly surprised a year from now with some results.
If you aren't convinced, take some good pictures of your hairline and compare to a month from now to see if you are really losing it quickly. It will also be a good way to compare to your results a year down the line.