I've got a laptop backpack I'm thinking of taking on an international then domestic United flight (itinary is EDI-EWR-MSY) as my only hand baggage. The bag is soft (so will squish down so it easily fits in a hand luggage checker at the gate, and will go under my seat on the plane if needs-be). However, the bottom sticks out slightly when not squished - so the dimension that should be under 22cm is more like 30cm.

Is this likely to be a problem? I can take a smaller bag if needs-be, but this one has good ergonomics and is well padded. The laptop bag is an older model of this bag (with slightly different dimensions) if that helps visualise it http://www.ebay.co.uk/itm/wenger-Swi...-/152307293428

Hope this is in the right place. Please move thread if not - thanks!