The previous comments are all valid so let me try to dig more into the question "why are you making these mistakes".
In general your moves give the impression of being both strategically aimless and technically flawed. I don't know what the time settings were but I wouldn't be surprised if this was a fast paced game. On these assumptions, I have a few recommendations:
1) play a slower paced game and/or use the time you have to consider a few moves and pick the one that seems to give rise to an acceptable sequence
2) apply basic technique or "haengma" such as one space jump for defense, keima for attack, don't attach to weak stones ...
3) apply basic strategic principles such as cut/connect on a large scale, attack/defend weak groups, play the largest area when all groups are strong
A few examples:

after a pincer, which denies a base, you could play the basic move for defense, i.e. a one space jump
(as pointed out, block at

and approach the corner at

)

instead of cutting aimlessly, leave this area alone and reinforce the upper left corner

instead of invading his base, build the upper side

attaching to a weak invading stone will make it stronger; attack from a distance instead, like with a capping move (boshi)
between 95 and 111 you have the right idea to build territory in the lower left center by attacking White's weak group; alas, you have to defend your own top group, which you have correctly identified as weak
:b111: Here you have to connect your big central string at E14, instead of connecting the worthless stone at G16. Now it's White who cuts and connects his major groups and you have no more leverage against him.
:b157: This move is not sente. Luckily the opponent answers. On the right side you can capture a stone. That move is worth much more. It's moves like these that give the impression you are playing on auto-pilot and not really considering alternatives.
Good luck!