I am a 31 year old man with spina bifida & I find the when I go to the restroom in the morning very little urine comes out of me. Is that normal?

Spinal Slowdown. This is not unusual in this type of condition since the nerves that control the bladder could be affected. In such a situation the ability to relax the bladder neck muscle effectively in coordination with the contraction of the bladder wall muscle to begin urination may be impaired. As a result the sensation to void could be affected as well as the ability to empty the bladder completely.
Experience teaches. You have lived with this problem 31 years. How long has this problem been occurring? If most of your life, then you have a "neurogenic bladder", common in spina bifida. But if this is new, consider inadequate fluid intake as cause of your problem. Sometimes an over-distended bladder will not relax readily after overnight sleep, perfectly normal.