Is is likely that my finasteride causes me to shed hair at 5 months

It is not likely at 5 months.  I have been prescribing this drug since it came on the market to possibly 10,000 patients or more. I listen to them and draw conclusions from my experience. At 5 months, finasteride is in balance with your body and the initial shed that occurs in some men, appears only in the first month or two.  If you are shedding now, it may be an acceleration of your genetic hair loss process