Why do i feel like im getting no where with my art?

[Wolf]

I love to draw it is one of my favorite things to do, but lately it seems i get depressed with my art, it is not like i draw depressing things it is that looking back in my artbook my drawing look like something my baby cousin would draw it jsut is depressing when the very thing you love doing seems to be all going downhill i try to keep my self positive and keep at it but i just cannot stay happy, i do not upload any of my drawings on the internet i have planed to and wanted to but for reason that even i do not know i just cannot get my self too. the only comments i do get are from some friends and although they are nice compliments there is no satisfaction i get i always think there is something wrong with my drawing, i also have alot of how to books and such but they seem to be doing nothing i practice alot also but looking back it feels like i have no improved, such as i have something i want to draw i have it in my mind clearly when i try to put it on paper i end up ripping it due to so many eraser marks, so my question is why do you think i feel this way what are some things i can do to help? and also i get jelous very quickly at other kids at school who are soo much better i like their drawings do not get me wrong but it seems i get even more depressed and i really would appreciate help in avoiding thins or how to deal with it and stay happy.
I know my question might not make too much sense right now or not enough information but i am just not too happy right now and am not thinking clearly just seems like what i love doing most is not improving.
i do not take art classes and yes i do know they help but as of now i am looking into it but do not feel motivated to go or even try to look for one so please help.
thanks for taking the time to answer it really means alot