You need to take the gear you have to a store and stuff it in a pack. It does not have to be the pack you want. Just see what Liter capacity you need. Just saying 1-7 days and light weight is not very useful- everyone's gear has varying VOLUME - and that is what you need to know. If you will backpack in an area that requires a bear can, then you need to take that into account. It takes very compact gear to do a 7-day trip in a 40L pack. Or are you going to have your poor GF carry everything that does not fit in yours, LOL. PS, my husband does this to me and I still love him.
If you do not like the style or look, just stick a pack cover over it and nobody will know the difference. Seriously, if bushwhacking, do stay with a clean outside so you do not catch on branches and be sure EVERYTHING fits inside. I once bushwhacked with my sleeping pad on the outside and ended up with a deflated pad- very uncomfortable!
Go for function first. Fine if you find a pack that is also "stylish". Otherwise, forget it.