Champion Mastery

So I have had two games in a row (ranked, I have played normals with her) with jinx with 19 kills and under 10 deaths. My averages are 17-7.7-9 with over 200 CS a game. But i have lost these games still. I was a cooperative teammate and and did everything i possibly could have to strive us to victory but alas I could not get it done. But somehow I am still not even mastery level three with her because losses dont get you any points. Riot, what i don't get it is how it makes sense to not give me more points towads my mastery when i obviously know what I'm doing. I'm not saying I am a master jinx player by any means but come on. I really think this mastery points reward system needs some rework. I shouldnt suffer in mastering a champion because I can't carry a team.