http://de.lichess.org/dRVb5RpB#21Dropping pieces to a simple pattern like that is no tactical weakness, that is an oversight or a lack of concentration. And you have plenty of those in your games.
Dude, don't offer draw to a much better player except your position is overwhelming. Otherwise this is considered bad etiquette. You did it repeatedly, that is unpolite.
http://de.lichess.org/nA58OEAJ#12Same here. e5, really? I refuse to believe that you don't see that taking back via dxe5 drops a piece. However, not having the immediate impulse of castling in this position hints at a lack of positional understanding.
Btw, let me suggest to never demand or accept takebacks. It would help you to focus if that takeback option is completely off the table.
http://de.lichess.org/8D9Iqxlf#24d4-d5 hurts my eyes, closing the position in your opponent's favour. This is a pretty gross positional blunder.
http://de.lichess.org/6xMIdrRI#18I already wondered what the bishop is doing on d2, but then a3 (instead of b3), allowing ...a4 and blocking the queenside. Again: basic positional mistake, once more in a kingsindian structure. Let's forget about the fact that a3 also drops a pawn and let me suggest to go for more open positions instead of these complicated positional/structural struggles.
http://de.lichess.org/XZidLSRt#52Here you want to instantly double your rooks on the seventh, that should take you half a second max. But you were exclusively driven by your desire to trade things down instead of positional instinct.
Good game!
http://de.lichess.org/xby1uMME#26Dropping a pawn in a simplistic way once again. Focus!
This seems to be a case where all you wanted is trade stuff and maybe get a draw against a much better opponent. Make the best moves instead.
http://de.lichess.org/SVYz7WNF#20After going 11.g4?? you lost the right to pretend you have a "good positional understanding". No, you are not there yet.
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Stop playing guys 500+ points better than you. Those are completely out of your league, and your play reflects on how intimidated you are. Play guys 100 or 200 points ahead, guys that are better than you but not out of reach.
And stop dropping pawns and pieces.