Just done a week in Malta with Ryanair under seat bag only.
washed one load of clothes.
16 degrees.
4x undies and socks 3x wool t shirts. 1 spare trousers ( wished I’d brought shorts instead !) . The secret emergency clothes of pjs that have black leggings style trousers and a flowery top .
secret bring jml vac pack thing - reduces what looks like a pack full of clothes to something the thickness of a decent hardback book and the size of the back of the pack if you are careful.
I even fitted my over the ear noise cancelling headphones in this time as I didn’t take spare shoes just my trainers.
wore long sleeved top ( washed and wore in return with a t shirt under as was freezing 🤣. Fleece zip hoody , soft shell jacket and waterproof . Oh and pashmina scarf . Needed alL if the layers in return 🤣
remember no one cares how much stuff you have till you go to the gate. I have a small back pack for day pack use ( decathlon it’s sbout 6cmx4cm when packed up and pretty flat ) and a nylon shopping bag that packs to nothing. Both v useful on holiday but lob all the coats in at the airport till you are called to the gate. ( and also remember the airport bag trick for your water and sandwiches ).
I also carry a Uniqlo banana bag under my coat with my valuables in. I make sure I can accommodate this in my luggage if I had to.
this is my backpack with a 500 ml water bottle on the side for scale.