“You can't use up creativity. The more you use, the more you have.” - Maya Angelou
Pulling ideas out of thin air, creating entire worlds simply from wisps of inspiration is hard work. It's a struggle to take what you have in your head and translate it into words, not just words but words that will conjure similar images in whoever reads them. Take comfort that the more you create out of the wild imaginings of your writer's mind, the more that part of you grows. It's like a muscle that needs to be exercised on a regular schedule to do the things we want it to do and to do them well.
Keep dreaming, keep writing, keep believing in yourself because the more you do the more you'll have.
Good luck and keep writing!