7 months on Finasteride. Still shedding at 100 -150 hairs/day. Is finasteride not working?

Thanks for your query.  Shedding of 100-150 hairs/day is absolutely okay. You can stop finasteride for a while and then start it again. This will increase the efficacy of the drug and you will see a better result. Along with that you can apply topical minoxidil twice daily and this will help in reducing the shedding of hair. Hope it helps.All The Best

Would first ensure the source of finasteride you are taking is legitimate and a good one.  There are many version of it generically.  If it is a good source, you can add minoxidil to your current regimen daily to further reduce your shedding.

Sometimes, the genes that cause hair loss are too strong for the drug finasteride to be effective in treating the hair loss.  

with any kind of medical hair regimentif anything , it will slow down the progression of hair loss but not stop it completely. We usually recommend to use it for a few months to see if it's working for the client. If not effective, you can add other treatment options to increase the efficiency.