It's so much better to use disposable cartridges in reuseable pens. Then you'll have less bulk to carry, cartridges take less room in your fridge than pens and there's less waste. As you're travelling next year, you have plenty of time to use up your current supply and ask to change prescription. Do you mean Humalin insulin - there are several types eg Humalin I? If so, Luxura metal pens take Humalin 3ml cartridges, as well as Humalog, in case you ever need a short acting insulin.
Cartridges fit easily into a 0.5litre stainless steel vacuum flask - you may already own one? When passing through airport security, flask needs to be empty, but at all other times, fill with cool water, ideally from a fridge. A flask gives far better protection against knocks and vibration, as well as extremes of temperature, as well as being far cheaper, than gel filled pouches.