Sleeping unwrapped and rolling worries

Our baby is 18 weeks and 3 days. She has outgrown her bassinet and is too long for it. Also she has been trying to roll while wrapped. So the wrap and the bassinet are out of use. She had started to become frustrated with the wrap more and more as she wants her arms up. So she’s been sleeping the past few days, not nights in her crib, with just a arms out, sleeping bag. The problem is she can roll very well from her back onto her stomach, but she doesn’t often or easily roll from her stomach to her back. So lately in the crib we stand in the room to watch her. Because she starts to doze and she raises her arms and rolls onto her stomach, the worry though is that she keeps her head face down into the bed. Even if we help her turn it to one side or the other she turns it back to face down. So we end up having a 5-8 minute tussle with her rolling her back on her back until finally she falls asleep. We do tummy time a lot every day. She’s very interested in following objects and what not. But she doesn’t seem too interested in rolling off her stomach. But if you put her on her back. Within a few minutes she’ll put herself on her stomach. What do we do. It doesn’t seem safe to let her have her face down while on her stomach in the crib.