To add on to what Legend has said, I would also check the operation of the rotor (he mentioned autowind assembly), make sure it rotates with the rotation of the watch without much drag or any physical impingements against anything else. There can also be an issue with the mainspring barrel (if it is slipping, etc). This is hard to detect and essentially will mean your watch cannot 'recharge' as expected and will have a lower 'max' power reserve.
As he said, you may want someone to look at it if winding it fully + wearing with physical movement of your hand/arms doesn't help.
Also reexamine your own physical movement with the watch on. Example, though I walk in my commute, I take my watch off at my desk (prevent scratches). The winding that happens with natural rotor movement would therefore be far lower than if I were to wear it the entire day, with 1/4-1/3 of my day moving around with my watch on.
