Is Propecia a Good Solution for Hair Loss?

In our practice, the only reason I ever recommend Propecia is to stabilize, not re- grow.
It's in your best interest to make sure there is not a delay in refilling your prescription.
So to answer your question, be happy you have hair and make sure you do everything you can to maintain.

Propecia is Effective for Slowing and Possibly Stopping Hair Loss Due to Male Pattern Baldness (Alopecia)

But it cannot replace lost hair follicles, and there is yet no known cure for permanent hair loss other than surgical hair restoration. 

Given that you started using Propecia at 19 and that your hair loss has slowed if not stopped, it sounds like Propecia has been a highly effective option for you. 

This isn’t surprising as an early National Institute of Health study on the effectiveness of Propecia found that the sooner you start using it after the first visible signs of hair loss, the more effective it is, and usually those visible signs start early, when you’re young.   You’re asking now “is it working?” I can tell you again that it probably has been quiet effective in arresting your hair loss. You should definitely be grateful that you started early and that it has worked this well for you.

Propecia's Effectiveness Might Be Increased by Combining It with Minoxidil

You may be able increase the effectiveness of Propecia by combining it with minoxidil or using a combination of Retin-A and  minoxidil.  However, you should never combine these drugs unless under the close supervision of your doctor. You should also be aware of the potential sexual side effects of Propecia and discuss the risks with your doctor.

You asked “how long can I go without taking my daily dose without affecting my treatment as sometimes I do have to wait for a new script.”  Generally, you should be fine waiting for a few days or even a week or two, but I wouldn’t stop using it for longer than that.

Propecia is as good as its results, which vary from person to person. SInce finasteride is targeted toward crown hair loss and does not affect the hairline, someone with a receding hairline would not say that Propecia is a good hair restoration solution. However, someone who needs to prevent crown loss would probably say it's great. Additionally, Propecia is most effective when use begins at the early onset of thinning, rather than when male pattern baldness has progressed to extreme hair loss.

The best way for you to determine if this medication is working for you would be to discontinue use. And there is no real reason for doing this, unless you're experiencing unfavorable side effects from the medication. Also, try not to go too long between prescriptions, as Propecia must be used continually to be most effective.