The dose of Finpecia
you are using 1mg is not that much high to show you the side effects. You dont experience any sideffects even If you use it for years together in the dose of 1mg.
Like you said turning your semen into more watery is not related to Finpecia usage it may be due to lack of proper protein in your diet .
But regarding dosage frequency,you better should discuss with your treating physician.