Thank you for writing!
Are you sure you have a small bladder, rather than an over-active bladder? Have you seen your doctor? You haven't given us much information to go on so I have some questions -
Have you woken up all throughout your life needing to use the bathroom or is it fairly recent (the past few years)?
For an overactive bladder, for women, childbirth and age are major factors.
The severity ranges from occasionally leaking urine when you cough or sneeze to having an urge to urinate that's so sudden and strong you don't get to a toilet in time. Or waking up throughout the night, as is happening with you.
It isn't a disease, it's a symptom. It can be caused by everyday habits, underlying medical conditions or physical problems. A thorough evaluation by your doctor can help determine what's behind your weak bladder.