Coil inductance measurement
If you don't have a model number and a datasheet then there is no use comparing it to the value listed on the inductor because the value of the inductance is not the only thing that can define the properties of a non-ideal inductor. There are a few things that can change the measured value:

1) Parasitics
 2) Self resonance
 3) Core material  

Parasitics - A real inductor has internal capacitance between coils and wire resistance, depending on the construction and especially at higher frequencies these can change your results of measuring inductance drastically. ESR can also be a big factor (the resistance from the coil of wire)



Self resonance - Because of parasitics (and other parasitics in your circuit) there can be a self resonance point, if your measuring near it it will throw off the value of inductance/impedance your measuring


Source of both pictures: Analog tips 

Core materials - If the core is not an air core but made of ferrite or some other material this will change the measured value of inductance. Ferrous materials exhibit hysteresis and will cause your signal to saturate. Ferrous materials in a core will make things difficult to measure and model.

What can you do about it? First of all, use more than one frequency, and scan several frequencies and plot it as in the chart above. Depending on the value of the inductor, run a range of frequencies 1Hz 10Hz 100Hz 1kHz 10kHz 100kHz and 1MHz. (after 10Mhz parasitics will usually take over unless they are controlled/eliminated) 

Account for the ESR, if your coil is large you can measure it and incorporate it into your equation.