do you bodyboard? because what you described sounds a lot like dking. I had that problem making the transition to surfing but practise will generat the best results.
A good thing to do is practise your popups at night on your floor as well. If your leading foot was anything like mine it will be half brained and zombie

But it will get a brain and start to work.
oh and this goofy/regular business when i first started i found it much easier to popup goofy but then later found i wasnt actually goofy footed

whatever your power leg is will more than likely be your back leg. Not always true i know someone who surfs regular and skateboards goofy

. so whatever works eh. but if you beleive you are regular footed then dont switch. Very few people have a switch stance between skateboard/surfing.
probably the best way to descide which footed you are is to try the following. Get a friend to stand in front of you and imaging you are bgoing to fight him. Now imagine you are going to round house kick him. what is your stance if your right is back then it means its your power foot and if left is forward it means its a leading foot and the balancing foot. If you have the mentioned stance then it means your power is generated from the right leg and waist therefore you can 90% be sure you are regular footed if you can do both with ease then umm seek help

there are exceptions of course. But its a good guide.