It is really very complicated to design and make a inductor choke as you experienced. But fortunately, in general, we do not need a so accurated inductor choke value.
When design and winding the inductor, do you know well the characteristics of the core you have? This is the most common mistake when self-making inductor. If you do not know, so you have to make some experiments to find them out.
On the other hand, how do you measure its inductance? Remember that its inductance is strongly dependent on frequency, current/voltage. To get its value, it is the best you measure when applying the inductor choke into the circuit with the same working/designing condition.
One more thing, you should squeeze the core (if you use the EI core) in the adequate condition when experimenting.
nguyennam