My daughter is 3 1/2 months old and still sleeps in her bassinet , when do I move her into the crib?

I'm concerned about safety. When I check on her she's turned crooked sometimes and is close to the sides. She hasnt rolled over yet by herself, even during the day, but when she's lying across my lap in my arms she'll kinda roll to look behind her. Is the bassinet unsafe once she's wiggly?