No problem !
I browsed your gallery, and according to that and the gear you already have, I will explain my point of view :
You have a Zenitar 50mm f/1.7 which is maybe not a very good lense (maybe too old ?). You have a kit lens, which is not a very good one too, but less old.
So if I think you need to change your zenitar if you think it's too old. That's my first point.
Second, according to your gallery, a 50mm seems fit your style. A 50mm f/1.4 is a very good lense, but it's not a zoom.
The 17-50 f/2.8 is good if you want to be flexible in the "dark". If you want to be good in the dark, the 50mm is enough (but your zenitar is also 1.7 ! So are you happy with that ?).
Another thing is : why another 50 mm ? You have a 18-55, so why ? If you want to shoot portraits, buy a 100mm macro lense and you will have beautiful macro and portraits ! Or a 85mm.
I saw the canon 50mm f/1.4 costs 400€ (in France), and the canon 100mm f/2.8 USM costs 600€. I think if you are patient, you should save your money and buy the 100mm to shoot portraits. Or try a 85mm.
I hope I helped you a little... As you can see I can't decide for you. I just told what I thought about it.