Phelan wrote:
Wouldn't a wide pincer at move 7 work better with the shimari? I would have played that instead.
Two or 3 comments on things that haven't been mentioned:
A few comments on your comments, and the original game.
I don't intend this as criticism, the comments are good, but I find the opening interesting and think that it is worth emphasising the breadth and depth of available good sequences.
5: As others have said these moves are fine, and you (oso) are thinking well about them. Your first 3 stones make a very well researched black shape, though it is no longer as popular as it used to be.
7: Good. This is the most common professional move by some way.
As has been noted, it is not obvious why this should be the case. It encourages white to make a strong group in the shimari's area of influence. The reason it is okay is that it is using that influence in a slightly different way - after the joseki, black has a good amount of solid territory that's essentially unassailable. White has strength, but no real territory...and white also has aji. At move 13 and onwards, both players are eyeing up G17 and F17 as massive points. If white takes F17, it is gote, but makes white much stronger...but gote at the wrong time in the opening can be a terrible mistkae. If black tkaes F17 it is almost sente against the white group, but if white responds (J15 is normal) white is even stronger than before and nigh unattackable. As a side note, white can ignore G17 and the group will be fine, but it will be difficult and complex to protect if it black invades, which white doesn't usually want.
So, essentially, black has used his shimari's strength to give white something to think about, whilst taking territory and sente to play (in this game) R6. This is a perfectly good way to use strength, you don't have to develop from it to get your full profit. Black even has, as stated, G17 later as a not unreasonable sente extension from the shimari.
On the other hand, playing a pincer to white's stone is also a very reasonable way of playing, and is clearly fine because it builds from the strength of the shimari. The two space high pincer (M16) is most common, essentially for reasons of joseki - the position is incredibly deeply researched due to its previous popularity. The one space low pincer (N17) is next most popular, for the same reason.
Phelan's suggestion, the two space low pincer (M17), is obvious to play but is not a common professional move for different reasons. In this particular position, I don't have a record of it being used at all. I think this is probably partly because the joseki variations just aren't good for black (a professional reason not to play it), but also it is too low. White wants to settle lightly here and make a good shape on the bottom side, and can aim to do this by leaning on the M17 stone. White Q14, for instance, seems likely to let white become strong - at which point the M17 stone may become weak and poorly placed. If it is pincered, black might prefer it to be high.
12: Oso: This is not slow, it is a very good move. It both makes white strong, and reduces the potential of the shimari. If white omits it, black M17 is a superb move which destroys white's shape and builds very nicely with the shimari.
15: Oso: Don't be so eager to follow through the territorial thing. If you take it too far, white just ends up with the entire centre and there's nothing you can do. The problem here is, R4 isn't usually great, because it's attaching to white's stone - but black doesn't need to do this because black isn't weak. After white R3, black has the problem that the R4 stone is weak, and white is looking to take the initiative. It is usually better to play S4 if you want to play in this area, so as not to cause this. Q10 is a simple alternative also, or maybe Q9.
17: Very bad, this stone does not help your shape. S3 is usually the correct move now, but I'll let you work out why yourself

18: You say 'What the hell?', but white's move is excellent. Black's stones have no base, and white has the entire corner in solid territory. White is very pleased with the situation now.
Edit: some more comments
21: Good, this is probably the most open area.
23: The three point extension isn't particulary normal in this shape, becasue of the H3 weakness. If white plays D2 now, black has a problem, and cannot settle by attacking because white is very strong on both sides. D2 is probably better, followed by C3 then J3 in most cases. That would leave black nicely settled and with the M3 extension available later.
24: This white move is very good, it severely limits the shimari, prevents black's sente/massive G17 move, and makes white very strong with territory on the top. It definitely does something useful!
25: Your plan is good, but you cannot just 'take the corner' consequence free. In particular, you cannot generally take the corner and also expect to take the outside - taking the corner will inevitably weaken the outer group because white can prevent the connection (but doesn't have to). However, your chosen move actually aims to
reduce the corner, which is quite reasonable. D3 is bad for the same reason R3 was, D2 is probably better for black.
27: Your move
is the shapemove. D2 is rubbish, if you have to play there then D3 was a terrible mistake. To look at it another way, D2 is the same as playing D2 first, white answering at C3, then black playing D3 - in this case, the D3 move makes no sense, it doesn't protect anything, and it invites white to take the corner. C2 gives white a couple of problems to think about, and offers an exchange, though a full discussion of the move would be very long

28: This is a classic mistake. You can look up why

.
35: Probably better to just capture. This leaves more aji at E4.
37: Bad, pushing from behind to fix the E4 weakness. It would be better to have played E4, and be able to jump to D7 now (if this is the area you choose to play).