Why am I so bad playing black?

When I look at that last game, I see these points. 

1. You've got better control over the center. After this your play is a little easier for you. 

2. Ask yourself the question after move 9: is your Bd7 happy? Is Nb8 happy? The goal is to always try and get the best out of your pieces. After move 9, your Nb8 can't develop. Your Bd7 is looking at its own pawns. Both pieces aren't really happy about all of this. Now, we can look at where this problem started. It's with 4. ... Bd7. This move was a mistake: it was too passive. 4. ... Bf5 is pretty reasonable. It also adheres better to opening principles: develop your pieces actively and towards the center. We can also work out a different setup for black. If Bb7 is not the right square and we think Bf5 is too dangerous, how could we have developed to make Nb8 and Bd7 happier? A setup could be to go for a Nbd7 and ...b6-...Bb7 setup. Then your pieces are out of eachother's ways. Still, Bb7 won't be too happy, because he's looking at his own pawns, so I still think Bf5 would've been a better square, but at least Bb7 isn't in the way anymore. 

3. Another thing to notice: white plays Nc3-a4 without having the other pieces developed. You play 11. ... Bd6 without the other pieces being developed. And then 12. ... Bb4. Yes, you could've just taken the pawn on move 12, but I just want to draw attention to how long it takes both of you to get all of your pieces into the game. 23 moves to get Nb8 into the action is a looooong time. And if we're being honest, Rf8 never did anything in this game, did he? You were essentially playing a rook down for a while. It pays to pay attention to getting all of your pieces involved and for them to get involved as fast as they can. 

So what you could take away from this is:

- develop as actively as possible. Don't be passive with moves like Bd7, because you'll rue it later
- develop every piece to active squares as fast as you can. Don't forget certain pieces, cause you'd effectively be playing down that piece.

Thanks again for comments

Another game I played tonight using the french which I think I played well, not without faults but felt in control most of it?

Yes, that was pretty well played. Even though your king on d7 did scare me while going through the game. 

but someone HMU

You did a great job, Waysandmeans

I thought I heard someone being disgusted with something today. I think it was the sound your bishop made after 14. ...b5.

On a more serious note: can you see the difference ...b6 makes to ...b5? After ...b6 your bishop can go to a6 and is doing something meaningful. On b7 it was doing nothing, but look at its own pawns forever.

I think playing black you're always at a disadvantage