Pop n grow help please

I recently bough some size 2 pop n grow for my 19 month old 28lb dd. I have snapped the poppers so they are on the smaller rise (if we don't we have major leg gaping). However when being used they seem to make themselves bigger my unfolding between the poppers so we get leg gaping. The poppers seem too far apart as they stay done up but the material kinda unfolds so the poppers are useless. Does that make sense? Is hard to explain clearly. What am I doing wrong?

Thanks

Not sure what's going wrong for you but I have a few of these and I've never been able to make them work. They always gape at the legs. I'll be stalking this thread to see if anyone has a solution.