I don't really understand Go

, however I might have some pointers for discussion:
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IMHO after a double approach it is usual to play 3/3 (C17) for settling. However your move, which is more center-oriented, might be also ok, I really don't know...
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I think the atari is from the wrong side: White secures the corner and you have some floating stones without a base. If you play D15 instead, it looks like you can easily settle your stones and take the corner for yourself (edit: in some variations the latter might depend on a ko, however in any case it seems that you will end up with a single group with eye shape).
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As C14 is practically dead, white is anyway connected. Therefore, saving the "cutting stone" on D13 is probably not the most important thing to do. Better try to improve the shape of the other stones, however I'm not sure about the best move here (H15, J15, ?).
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Your upper left group still needs attention. Actually in the game, the group finally died. Therefore at this time, it would be a good opportunity to reinforce the group.