I totally understand your struggle with the carry - on weight issue. It's really annoying when you're constantly restricted by these tight limits.
One thing you could consider is packing travel - sized, multi - purpose items. For example, instead of bringing separate bottles of shampoo, conditioner, and body wash, look for a 2 - in - 1 or even 3 - in - 1 product. There are also travel - sized laundry detergents that are super light and can be used for hand - washing a few items if needed.
Another option is to invest in some lightweight, quick - drying fabrics. Merino wool is a great choice as it's not only lightweight but also odor - resistant, so you can wear the same piece a few times without it getting too smelly. Synthetic materials like nylon and polyester also dry much faster than cotton when hand - washed. You can find quick - drying travel towels too, which are much lighter than regular towels.
If you're traveling to a place where you can easily buy inexpensive clothes, you could plan to buy some basics there. For instance, if you're going to a tropical destination, you can buy a few cheap t - shirts and shorts when you arrive. Then, when it's time to leave, you can donate or discard them, reducing the weight of your luggage on the way back.
As for the laundry situation, some hostels offer shared laundry facilities at a reasonable price. Even if you're not staying in a hostel, you might be able to use their services for a small fee. Also, look for mobile laundry services in the areas you're traveling to. Some companies will pick up your laundry, wash and fold it, and deliver it back to your hotel, which can save you time and hassle.
Hope these suggestions help you make your travels a bit more convenient!