Leveling up too fast

I feel that it is too easy and too fast to level up. I have not been playing for very long and I do not know what I am doing half the time (I also want to say that I did do the tutorial). I just learned what it means to build a champion today but I am level 21. It has become very hard for me to play with other people in the same level as me because I leveled up way too fast and learning slowly. I have asked my friends who play as well and they have the same concern. If it is at all possible to slow the level process down so I can try out some champions and figure things out as I go like build, runes, masteries, etc. I need the time to learn champions, 3v3's are great for that but you cant decide if that the champion is really going to work until you actually try it out in a rift game. One of the big problems that I am also having with this is as I level up the other players think I should be really good at the game. I get reported for feeding, "giving up", etc even though I am simply trying to play and learn the game well. I know that I am not good but atleast I try, I would like to stay lower levels and actually earn leveling up not just having it given to me. I would like this so I do not get reported for things I try not to do and get angry comments from others. I really hope that you understand my concern. I would love to continue to play this game, but it is irritating when I level up so fast and I really have not learned anything. I really appreciate your time and I hope that you can take this matter seriously so we can work on this. Please let me know your thoughts on this as well. Thank you, SapphireMeow