I hope you don't mind me jumping in here.

I didn't read all the other comments so I might say something that was already said before.
East 1: I would discard the

and then

, but this is very minor. I think you played this hand really well though.
East 2: When you discard

dora, I think both

and

then

are possibly better, but I don't think

is too bad. You might notice the dealer held on to 2 honor tiles over the

and

, which looks like honitsu so that's another reason to hold the dora (as you can use the other bamboo tiles as well if you draw them, and you don't have to worry about it getting called). Personally, I wouldn't declare riichi but I don't think it's bad to. I think you played this hand fine as well.
East 2 bonus 1: The

wasn't very useful as

and

would go with

(of course 7 would go better with 8 though). If you are considering hands other than chiitoitsu, you should hold

cause you can draw around it and use the dora. If you're only thinking of chiitoitsu, you could consider holding

and discarding middle tiles like

. Once you get a triplet of

I would discard the

for sure, and multiple times later on as well I would discard it.
Near the end, you could call the

with the plan of discarding

, so you have a chance to get to tenpai (safely even).
The last

discard was risky.
East 2 bonus 2: When you discard

, it's an interesting decision between that,

and

/

. I can't say which is best for sure, so I'll just go off of your choice. After that, you should discard

as it has very little use. It could be a pair, but when you draw

you have 2 pairs already. I think both discarding the

pair and the

before the

to be big mistakes. With the two pairs you're one away from tenpai with 2 dora and a chance to draw a good wait around the

. You can't draw much of a wait around

because

is furiten, and the 4567 is better anyway. You actually drew a

, and would've been one away from tenpai on pinfu, 2 dora, possibly tanyao. Even after the riichi,

was safe and not very useful to you, but

wasn't safe.
Of course, you may not have won this hand any way you played it, but you want to make sure you're making good decisions anyway.
East 3: Discarding

from

was not a good discard. You are one away from tenpai and could get pinfu if you draw

. Because the 6 bamboos are your pair, you should discard 4 bamboo.

is more useful than

, especially when the 6 is separated out as a pair. In the same way,

in

is more useful than

so I would discard 4 bamboo there as well (think of both the 4 bamboo and 3 crak as lone tiles). I don't like discarding

, but with three 6, three 8, and a 9 circle out and the chance at sanshoku I guess it's fine.
East 4: I don't have much to say here.
South 1: When you discard

I would recommend

(even if you draw 7 bam it's not completely wasted, and you can use the dora). If you're going to pick

though, you should go with

instead. As for the actual result, there's nothing you could do about that.
South 2: Nothing to say
South 2 bonus 1: I think you played this hand just fine.
South 3: I would hold

for sanshoku chance and discard red dragon. It's unlikely but it's desperation time.
South 4: I would call pon on the south wind and hope to win with 2 dora, double south wind off of the person across from you.
You can very easily get really unlucky or really lucky for a while without playing much better or worse. Recently, I got like 7 last places out of 12 matches in the tokujou room, despite playing in the same way that got me to 7th dan, and after that, my past 21 games have been 6 first, 7 second, 8 third, no last place, without making any major changes. All you can do is try to make the best decisions possible...