Confused

Is there a certain time frame that MMR updates? Or is there something wonky I don't understand? I'm taking my alt account to gold+ and have gone 16/4 in my last 20 games in the last few days and have gained 2.5 divisions so far (low for what gains I should really be getting). When I check sites like na.op.gg it says my mmr is lower than where it should be, and I'm only getting gains of like 14-16 per win. I'm trying to understand this whole hidden mmr thing and seeing why even though I'm winning 4x more games than losses, my gains are still extremely low on this account and playing with people divisions below me. I mean I shouldn't be mad, easier wins to climb faster but it still doesn't make sense.