First you should know that most of the sites that calculate MMR are very loose approximations. They are good reference points in figuring out if you are playing well or poorly against players above or below your MMR, and if you are likely to lose your rank if you lose your next game, but they are by no means accurate or representative of Riot's actual MMR calculation.
Also your normal mmr and your ranked mmr have nothing to do with each other they are completely separate ranking systems. I am going to only refer to ranked MMR in this post.
Now, if you played ranked with friends that were lower elo, it means that you were probably playing against people with an average or lower mmr than yourself.
This means that you should be able to beat those players and thus not really gaining much LP and it won't effect your MMR much even if you win.
If you are a Gold 4 or 3 player and you play against Silver I or 3s, beating them is going to grant LP but it typically will not raise your Ranked MMR.
However, if you LOSE to those players, you may not lose much LP per loss but your MMR will drop. Then the ranking system will try pair you up with players that are closer to what it thinks is your skill. So your LP did not really change per loss or win after one game, but your MMR might change.
Actual LP responds a little bit later (if you go on winning or losing streaks). How much you earn or lose per game is largely contingent on your streakiness and the skill of your opponents. If you lose several games in a row your LP per win will be lower and per loss it will be higher and vice versa if you win a lot of games in a row.
Your MMR is being affected in this time, but changes in your LP gained/lossed per game takes several games in a row to be significantly effected.
That being said, most people do not really understand how LP per loss or win is calculated, but we do know that if your ACTUAL MMR is high you will earn more LP per win and if you MMR is low you will earn less LP per win.
I doubt you are a platinum caliber player if you are sitting in low gold with that many games under your belt.
Even if your win rate is high, you haven't played enough champions or enough games, for it to even out. Once you start playing against better players your rates will begin to drop and come closer to 50ish percent.
There is a significant difference in player skill from Gold V to Gold III, and another notable change in high Gold. Sure you may be stomping high silver and low gold players but once you start playing against high gold or mid gold players who have played in the division awhile you will probably have a harder time climbing.
I am sitting in Gold II at the moment and even though I have recently bounced around in Gold II and Gold I, I know that I have improved since playing in low gold most of the season, but probably not improved enough to get to platinum without going on a hot streak.
My top game is low platinum caliber, but my off roles are not, hence if I don't play my main role and main champion, I lose more often than I win. Which is why I sit in Gold, because other aspects of my game need to simply improve.
