This is a really common issue. I think the key thing a lot of people miss when transitioning to the swamps is good food. Food is at least as important as gear in this game. Make sure you've got a good carrot patch, and it's not too hard to be eating carrot soup and deer stew at all times. Prioritize finding turnip seeds on your first couple swamp trips, and then you can upgrade your food even further and everything gets much more comfy.