New Rank System

I'm confused. I got to gold 1 as top and never played anything else.

Then, I decided to try other lanes as well in Ranked, lost two games then won two. When I que back top I am now gold 2 60 lp and only get 20 LP a win compared to the 28 I used to get? What happened? Am I only allowed to play one role in ranked, or?

This new system is confusing and I miss the old one.