Silver 3 ranked won but....

So, I was playing a ranked game because i want to climb the ladder. We won the game since the very beggining and we won every teamfight, they had no barons nor took down 1 of our inhibs. they never where even close to winning. When we won the game, i went to the aftermatch stats to realize that I only got +9 lps and I was freaked out, then I noticed that my whole team gained the same as me and the enemies got "Loss prevented". Look at the gold difference (we are in the blue side): https://gyazo.com/caa06dc952d197cdb201bf244bd55a70 . Can someone explain this to me? is this a bug or something? will i get my real lps? :(