Here I was thinking I would move up

+16 when at 83... that's garbage.

I thought it was bad when I got +17 when at 80...

Honestly, it isn't hard, let LP go above 100. Just keep it as a rolling number. If you're at 99 and win and go in to promos with 117, then lose your promos, you end up at 95 instead of at 82, and thus are guaranteed to get back in to promos after just 1 more win instead of 2 again.

I only have a slight problem with ending up at 95-99 LP once. What's annoying is ending up at 97LP, going 1-2 in promos, getting put back on 80LP (so already, I went 2-2 and dropped 17 LP), then winning and getting put back to 97. 3W-2L should never result in a 0LP move...

Its because your mmr is lower than Bronze 2. To fix this go on about a 7 game Winstead and you will start getting 30 LP a game. This is how I got out of bronze.