The model, who lost the baby she was expecting with Evans in May 2011, said she has accepted that life can be unpredictable.
"I just take every day as it comes," she told Look. "You could say one day I want to be married, or I want to have a child, but you never know what life is going to throw at you.
"My happiness is about what's going on inside me, not whether I'm alone or not. I was happy single and now I'm really happy in a relationship."
Brook commented at the beginning of the year that her relationship with Evans was strengthened by their baby tragedy.
The rugby star recently admitted that he found Brook's beauty "overwhelming" when he first met her.