It's pretty spot on... I might just have a bad memory but I don't remember any manga chapters not featured in the anime. On top of that, the adaptation shows the manga in even greater detail, painfully so. I wouldn't worry about missing anything.
some of the early chapters weren't animated and the character naito longchamp was completely written out (not that he was ever important though) and there is some filler in the future arc but that's to be expected, its certainly not bad filler though. its also toned down a bit compared to the manga but mainly that there isn't much blood shown in the series but overall they do follow pretty closely.
Oh okay :D I was just worried they might change the plot suddenly like they did in Kuroshitsuji season I, but now I see that it's a little bit like Bleach eh? Or something, I don't know. If it's just fillers I won't mind, I'm just worried I might miss something drastic, or something of the sort. Thanks for your help though! Much appreciated~