Nice game.

A few remarks (If you don’t have the time or don’t want to read all that – The remark on move 49 is by far the most important):

Move 6 – Nice thinking. definitely, a 3-4 corner can be finished in one move, so approaching it is usually considered better than the wedge played. If black’s top left was a 4-4 stone, then wedging is an actual possibility, in addition to approaching.

Move 9 – Generally, the 3-3 IS always open with a 4-4, however, care must be taken to realize that there’s a huge difference between replying to a pincer with a 3-3 invasion, to replying to an attachment with a 3-3 invasion. In the latter case, your approach stone is much weaker and a lot less usable after a corner sequence to settle your invasion.
Especially if you’re already a 5k, as it seems, and looking to improve, it’s useful to remember that these 3-3s in reply to attachments are special case moves… and that in general, just going into corners after severely weakening our own outside stone is a bad strategy more often than a good one.
There are exceptions of course…

What I was wondering about is – you said you feel unsafe in the attachment joseki… I wonder what you meant by that? Because the position you would get on the outside is quite safe and not really open to attack.
If you mean that white seems to get a lot in those variations (he doesn’t…), then a simple explanation of why what he gets is not that big can be given…

Of course it does not become a problem in this game as you have noticed a few moves later –

Move 12 – Indeed, your opponent’s move is a mistake, as you’ve pointed out 🙂

Move 20 – Personal opinion – this k3 move… White has to play it high (4th line). If you get to shoulder hit this later he gets next to nothing with all his stones like that on k3… Although harder to complete the shape on the bottom after K4… But white has to play for more since he gave you so much cash and takes only potential, he needs to make it bigger to have a chance to win.

Move 21 – The variation you show at P3 is….. well, you’re missing something a bit simpler for white after the cut and attempt to capture… But there are things black could change there too 🙂

However, the problem with P3 is that it gets under an immediate attack (Q3) which would give white solid territory in sente and make you the proud owner of an unsettled group for no reason…

On the same token – you were right about E16 being a good move. But rarely is a move so early in the game good if it does only 1 thing. This move is good because it reduces the pressure on white’s top stone, while at the same time reducing black… So – you could have attacked white (before bending) from the same direction… he pretty much has to reply on top and you can bend there for a really massive potential.

Move 23 – A = I wouldn’t… white’s group still has weaknesses and you want him to either be attacked there or to have to spend gote moves to fix them later…

Move 49 – This is what I consider a very important moment in the game.
I consider it as inviting your opponent back into a (much closer) game.

First – what actually happens in the game is that white massively overplays his hand…

What bothers me is what could have happened, and your reasons for selecting this move.
This stone might not be possible to capture… However –
That is not even important here, and not what makes an invasion good (definitely not a sufficient condition by any stretch of the imagination).

The factors to consider –
Is this move attacking ? Even after the move white plays in the game (which is probably a good response…), you can immediately see that your own stone is weaker. White is by no means forced to go berserk and allow himself to be cut later. white can go out, and keep going out as he’s chasing your stone…
So – if this move isn’t really attacking (all it takes is 1-2 moves to see that your stone is the weaker one), why was it played? Where’s the profit?
If it’s not attacking or defending, it has to be a big move to be good… Is it? White has only 10-15 points in that area for now… (only ~10 guaranteed for now). With so many stones there. In sheer size – the bottom right area is just bigger…

But all of these are secondary to the most important factor of all – you’re creating a weak group. Sure, it may live. but a group can be sure it cannot be killed and still be weak.
you’re playing next to a strong white position. „Play away from strength“ is probably one of the most important Go proverbs out there…

So – what could have happened (assuming there’s really no way to kill that stone) – white could have jumped out just as in the game, but kept running out towards the right (instead of playing the horrible one space jump into a pre-existing peep).
As he chases your group to the lower right quadrant, he gains a few moves on the lower-right or lower edge. Basically making the bottom right a lot more solid while gaining stones in the center as he runs out (which, incidentally, could help him reduce the left…)

Since you have a weak group there, you would have no time to react to any of it.

Creating a weak group for no reason… that is the problem.
Other good options exist.
reducing that bottom potential (by either capping or shoulder hitting), approaching the lower right (high, if you want to avoid an attack)… But do you really need to get under a one sided attack for an area which has only a few points in it? Actually, even if it’s a much larger area, if you’re not behind, you prefer to not make weak groups at all…

It’s very easy to lose a game without having a single group die if you make such weak groups.

(un)luckily for you, your opponent went berserk, and you just dominated for the rest of the game. The mistake in the next invasion are less important since even if white had killed the invasion in the bottom right at the start somehow, black was already too easily winning.
Very nice game to look at overall 🙂