I was a bit socially awkward when growing up. (Maybe I still am, but that's a topic for another day.) Anyway, when I was in junior high school, and I finally found a small group of mixed gender students in my grade that gravitated to each other, I often found myself feeling tongue-tied, unable to find anything to talk about on the spur of the moment. Then I figured out that a bit of advance planning allowed me to participate in a seemingly off-hand comfortable way. Throughout the day, at school and at home, a small part of my mind would be monitoring my thoughts and if a stray thought came up that would work as "conversation material," I would make a mental note. (If necessary, one could make an actual written note, too.) Then on my way to school in the morning I would review my mental notes. Usually I was able to prepare one or two comments per day to my friends in this way, and that was enough to break the ice.
During this early period with your Russian, and your new co-workers, you'll need to explicitly plan ahead in a similar way.
There is no reason not to repeat the topic with a different co-worker at a different time.
You might want to write down three to five key vocabulary words for the planned topic, on an index card to keep in your pocket. (You might or might not need to pull it out to remind yourself during the informal chat.)
That was my first suggestion. My second suggestion is to start by playing a card game or a board game with some of your new friends. This will have a limited set of words and phrases that can get used over and over again, and it will give you something to manipulate with your hands. Here, again, an index card cheat sheet will be very helpful for you.
Third suggestion: learn some get-to-know-you interview-type questions, such as, "Do you have children? How old are they? Do you have a photograph handy?" or "Did you grow up in name-of-city-or-region? [If no:] What brought you to name-of-city-or-region?" Draw the other person out as much as possible. Repeat in your own simple words what the person has said, from time to time. In this suggestion, the theme is empathetic listening. To overcome self-consciousness, focus on the person and getting to know what makes him or her tic. That will help distract you from feelings of incompetency or self-consciousness.