If your humidifier isn't doing raising humidity substantially you need a better humidifier or a smaller room to contain the humidity (as mentioned by others). I noticed major improvements over the winter by adding a humidifier and keeping humidity between 45-60%. I struggled with keeping a smaller humidifier topped up and with its generally low output. This humidifier finally did it for me:
6L humidifier
Note that this humidifier has a max room size of 430sqft. I'm able to keep my humidity up in a room a bit larger than that but it takes some time if starting at a low level. The humidifier runs for 20 hours on high and 60 hours on low. I use high to get the humidity up then I refill and run on low- this has been a game changer for me. Remember to clean your humidifier at least monthly (with bleach) as they can easily grow moulds and mildews.