What the hell is wrong with my MMR?

About 2 months ago I was Gold 3 and then I stopped playing because of Overwatch. When I started playing again I tilted myself really hard and went back to Gold 5 0 LP. My MMR dropped to Silver numbers.

Recently I started winning alot of games and I'm a game away to Gold 3 again. When I check my MMR on op.gg not only it doesn't grow but it's getting lower and lower even though I've won 6 in a row with good performances in SOLO queue. It keeps matching me with high silvers/low golds and even though I'm far from a god, in terms of skill and game knowledge I'm definitely better than this. What's the point of climbing if my MMR stays ridiculously low?

Why is this happening?