Hello,and welcome to the forum.
No,your problem is not
It is one of a few things;
The new battery you have is faulty
You have a drain on the battery that is flattening it if it's left for any period of time
You have a faulty starter motor
The engine is beginning to seize up!(unlikely)
I would have a drain check done (ammeter between battery negative terminal and disconnected earth lead) to determine if this is the case.
Have the battery tested under load to determine if it's O.K
If the battery is O.K and no drain,then suspect the starter motor.
And one other thing,check you have a good engine earth.