I'm an urban rider myself in Brooklyn and Queens NY, so I feel your pain!

I felt the same way as you when I came back to riding - unsure, abit unsteady, indecisive, bad shifting, etc., etc.. But with time and perseverance, I did get better and more confident. But even now, there are time's I just won't take out my bikes. The traffic is just to heavy, and the people just to impatient. For me, the middle of the day is best, when their are fewer cars on the road, and even more important, fewer parked cars, as I really worry about that car door opening up on me!

Sometimes I still think I'm crazy for riding a bike here, but those times are much fewer now and I've come to slowly realize that I have as much right to be on the streets as any other vehicle. So just give yourself time, you will get better and gain confidence...