Your math is all wrong in order to translate the output of a 3.7V battery to a 1.5v battery you have to convert to watt hours and convert back.fivemega say's .........
In fact, you suppose to get 1.5V out so:
3300/1.5=2200 mAh or 2.2Ah
If you test it with 1A discharge, you should get:
3.3A (3300mah) x3.7V= 12.21Watt Hours. 12.21/1.5V = 8.14Ah. so you could get 8 hours but taking the losses in conversion likely closer to half that or 4 hours using a buck circuit so if you are getting less than that likely the battery is less capacity than 3300mah. There is no saying that they can't put a 2600mah battery in it and use a mediocre circuit and get less than that.