Struggle with small talk

I don't have any answers for you because I suffer from the same thing.

I suppose what helps me is a couple of friends that know me and accept me. Ironically I tend to talk their ears off (it's about feeling comfortable I guess). But in unfamiliar social occasions or meeting new people I do tend to clam up and it's a pain. So I feel for you.

Most of the time I just try to think of an ice breaker question.
For example, I recently moved to Germany and met an american who was here visiting his girlfriend, we got left alone for a couple of hours before meeting with a group of friends. Of course I was like aaah crap, is this gonna be awkward?
So, I just said to him "so, do you think Europe is different to America? What stuff have you noticed is different?"
And it developed into a conversation that lasted the whole 2 hours about differences between the states and Europe, what I have found different within Europe, etc.

A lot of the time, the other person feels awkward too and it's about making them feel comfortable to talk to you. I often do this by just being interested in whatever small facts I know about the person I'm talking to.
You just need to put yourself out there. At first it feels so awkward but eventually you realise that after 5 minutes of it being awkward, you can make someone feel so comfortable with you.

I have recently moved back to London to a house full of other people.

Thing you need to know about me is that I've always been bullied about my weight and I dealt with it by just retreating to the background, by not saying anything, so hopefully no one would even notice me.
Also, the area I come from it is just not a cultural thing to always have to fill up silences. In my family we are perfectly happy just sitting in silence.

Now that I have moved to this new house, my housemates keep telling me that I am very quiet and that I am bad at small talk. They tell me that the silences are making them a bit uncomfortable and they feel like I don't like them. But I just don't know what to say or how to even start.
I used to suffer from severe social anxiety, so much so that I wouldn't go out for months. So I have come a long way already, I just don't know how to do this one thing.

How do you people do it?
What do you talk about and how do you avoid awkward silences?

that's rather rude and unhelpful of them to say that. some people are just quiet.

my advice is to smile, and to make eye contact when they talk to you. if you seem open and attentive then instead of being 'quiet and creepy' you're a 'really good listener!'.
it's easier to ask about other people than it is to talk about yourself, and that wins you brownie points too. look up 'active listening' and you'll get an idea of what i mean. let the other person do the conversational leg work.
relax your posture. if you seem relaxed then people will feel more relaxed around you. so head up, shoulders loose and smile at the ready!

I cannot stand small talk I avoid it as much as possible, I also suffer from social anxiety. My only advice is to talk about things you're interested in I find its easier to hold a convo that way without stressing about what to say next. If you can't do that then just say you're not much of a talker. Or maybe think about ways of reducing your anxiety if you really wish to be able to engage in small talk. In my opinion it's perfectly okay to stay silent if you wish, we don't need to fill every second with words just to appease someone else.

All the best xxx

The book, "Quiet: The Power of Introverts in a World That Can't Stop Talking," by Susan Cain is a good read in spite of some of the chapters being a bit on the pop psychology side. I am an introvert, but it is not grounded in social anxiety. It is the way I "process" my environment.

What most posters here said is true. Demonstrate geunine interest in other people (those "extroverts!") and they'll love you to pieces.