Since this is your first exp. with extensions of course there will be some paranoia, but continue to work on the part & getting comfortable with them being in. Also, if you get the extensions cut/trimmed, they won't be as heavy as they are now. If they are, then maybe you do not need to put in as many...that's something that you should talk over with your beautician.
I do not have any experience with clip in extensions, but have had hair sewn in. I think that's what I'm going to go with since I won't have to worry about my hair's response to the humidity. Also, my hair is shoulder length so I think I want to add some length to it for an updo.
Having said all of that...just make sure that you are get completely comfortable with your hair bcuz you shouldn't be worried about that on your Big day.