One thing that pops into mind is why are you feeling it neccessary to be perfect? Why are you putting yourself down? Have you been told this or learned it from somewhere? In who's voice is your inner self being critical of you? This may be the source of the issue and not merely being unmotivated. Is there something else that needs to be addressed?

It is good that you are reaching out - and welcome as I see you are new - but I would like to see you reach out to a real life person too. Do you have a school counsellor? As this might be depression - or another psychological disorder - I suggest seeing your doctor - in most countries you are old enough you don't require permission and for your medical history to now be confidential. A doctor can help point you to resources. Another resurce is a kids/youth help line, I think there is an international one too.