I don't really know why half the people even commented on your problem with irrelevant comments.
that just sums up the world of fashion for you - bitchy.
anyway, i have owned quite a few all saints leather jackets... all saints is known for its tight/slim fitting, it always recommended to upsize if you are wanting your regular fit.
the jacket doesn't look bad... why would you want a baggy leather jacket? it just wants to fit properly... it is slightly on the tight side. if you got the next size up you probably still wont be happy with it, the only thing will change is the chest size, the length will be very similar if not the same..
the only problem you have with your outfit is the choice of t-shirt.. you should get a lower more casual fit, slightly longer in length. it looks strange because your t-shirt is shorter the the jacket.. and the neck of the t-shirt is higher than the collar of the jacket.. honestly if you get a looser t-shirt (which are highly in fashion by the way and you can find some great ones) even all saints do some decent ones.
honestly, if you get a longer t-shirt with a slightly lower neck it will look a lot better.
don't listen to these fools about the jeans, anyone can pull off skinny jeans if they want to. the people who look most ridiculous in skinny jeans is those who don't fit into them properly, you look fine.
all i suggest is that if you do feel the jacket is too tight, get the next size up.. although remember the length won't really change, only the chest size.. which will obviously make it a little less tight..
but follow my advice on the t-shirts!
btw, i'm a style advisor for vogue, i only came across this thread because i'm looking for this jacket my self!