Sounds like its been enough to keep him alive. However is it your goal to just keep him alive, or have him grow to his potential, and live a life of sound health?
He should be eating mice and small rats at that age, and be much larger. Niloticus at 12- 18 months are commonly 5/6' , when kept in encolsure that allowe access to consistant heat/ food sources.
key factors...
1. Temp/ basking gradient, with MANY choices. (lows in 70s to highs near 160).
2. MANY hides in various temp ranges.
3. Regular feedings, based on animals appitite, body condition, and age.
4. Access to fresh water at all times.
5. A large enclosure that allows for proper air circulation AS WELL as maintaining proper humidity levels.
I know of a man who lost his entire WT collection due to having them in such airtight/ stagnent troughs, that they developed bacterial infections in their lungs. While proper humidity is important, fresh air is just as vital, but goes neglected many times.