I have been cleaning for a little longer than you 10-11 months , i also charge £1 per window/door and doesn't matter if big or small still a pound first cleans add 50% to 100%, Better to price like this then if a customer says thats too much then you can do a deal with them, but beware of doing different prices on the same house types, same area's they may know each other and want a cheaper price.
If no one has said anything and your getting the business don't worry, You might find other cleaners in the area are cheaper,however there is a chance theyv'e not increased there price for sometime.
Good Luck and stick with it, you will make a good living.