Personally I dont think there is one correct dosing amount/method. It is more about being consistent and getting your technique to the point where you can be fairly accurate between doses, which requires practice.
If you think you are putting too much coffee in why not down dose a little. Instead of leveling off with a straightedge use something curved. You can use your finger to do it, but if you want to ensure consistency then use the other side of the knife or something you have curved. If you decide you want to updose then introduce a tap or more at halfway or when the basket is full of coffee.
I imagine if you asked people how they dose on this forum you would get a lot of different opinions. For instance my standard dose is fill half way, tap three times, fill the remainder of the basket, use the stockfleths move and then level and tamp. If I want to downdose without adjusting the grind I might not do any taps. If I want to updose without adjusting the grind then I introduce taps after filling the basket.
My advice would be to play around and see what works for you and what gives you the result that you desire.