Sandwich bag

I made a sandwich bag from this web site. I had a real hard time working with the plastic baggie. Maybe its just me? the plastic didn't stay still even when I pinned it? But I thought it wouldn't matter too much but I don't think a sandwich will actually fit in it?

This is the flap on the back.

This is the top tucked in.

This is it opened up.
This is it closed with no sandwich but it looks way too small to fit a sandwich in it?
Maybe its ok I will test it tomorrow with a sandwich.