Sorry, you went 1-15 over 16 ranked games on Feb 4th-5th.
Meanwhile, your longest winning streak has been 4 games, generally followed by a similar losing streak.
In short, you dropped 300MMR and you still can't win more than 50% of your games, therefore the system considers that you are where you belong. You are in the 500MMR bracket, to give you some context Bronze V is considered ~800MMR and Silver V is ~1200.
Streaks makes LP changes accelerate, both ways. If you keep winning, the system will start putting you in increasingly high MMR games until you it finds where you belong. It works the the exact same way for very long losing streaks, except matching you with weaker and weaker opponents.
Easiest way to dig yourself out would be going on a very long (15+) winning streak, but since that's unlikely, you'll just need to grind MMR the hard way, trying to maintain a 55%+ win rate over 100+ games.