Has anyone been able to take this much luggage on the ferry to Capri from Amalfi?
Possibly, but I suspect no one on this forum has taken that much luggage for a 14 day trip.
If you bring that much stuff with you, I suspect you will regret it.
What size is "large" ?
I am having trouble visualize how one person can move one large bag, one carry-on bag and a garment bag.
On the Amalfi coast there is very little level. Mostly up/down and cobblestones.
I do not think we can reduce the amount of luggage. But, I see your points. Capri may be out of the question as well as traveling by train.
How are you getting to Amalfi? Unless you fly into Naples and have a car service pick you up at the airport, a train or bus is unavoidable.
You do not say how many different places you are staying, but if it is 3 or more, I suspect you will have some thoughts on what you really didn't need to bring, that you currently see as 'essential'. Even on the Amalfi coast there are laundry services; you can have clean clothes every day without having to bring 14 sets of everything.
Think harder and remember your honeymoon for something other than being 'pack mule.'