If you're in silver 2, and gaining 17LP per win losing 22LP per loss, you don't have Silver 1 MMR.
Sites like OP.gg may give you an MMR rating, but it's inaccurate. No one knows your true MMR. However, your MMR is what determines your LP gains and losses - so if your MMR is higher than your rank, you'll gain more per win than you lose per loss (so you'd gain more than 20 and lose less than 20), thus, we know your MMR is actually lower than Silver 2.
An 11 game win streak is definitely impressive and your MMR should increase with that (even though you've played over 250 games, so it's not going to affect your MMR as much as if it were in your first 50 or 100 games, but still...). Did you notice your LP gains increasing throughout the streak? e.g. did you start at getting only 15 LP per win?
I have to assume that 11 wins in a row made you climb a division or two. So while your MMR is rising, so is your rank. You may have started with bronze 1 MMR in silver 4, and are now silver 3 MMR in silver 2. You've closed the gap, but your MMR hasn't passed your rank yet.
Just keeping winning more than you lose, and it should get back to around 20-20.