14 months of progressive shedding that hasn't stabilised is not a normal shed pattern. Most finasteride sheds peak around months 2 to 4 and resolve. What you're describing, ongoing diffuse thinning across the sides, hairline and nape with no sign of stopping, is worth taking seriously rather than pushing through.
A few things worth considering.
The sides, hairline and nape thinning is unusual for a standard finasteride shed which typically affects the top first. That pattern is worth getting a dermatologist to look at. There are other causes of diffuse loss that finasteride won't address and could even mask.
On dose. Going from 0.5mg to 1mg at this point without understanding why you're shedding is a risk. If this is a poor response to the drug, more of it is unlikely to help.
On stopping. The fear of getting stuck is understandable but if the drug is not working and may be contributing to the problem, staying on it out of fear is not a strategy. Most people who stop see the shedding slow as DHT normalises. Getting back to baseline takes time but it does happen for most.
Get a proper in person assessment before making any changes. Blood work, scalp examination, the full picture. You deserve an actual diagnosis not more months of hoping it turns around.