Sleeping & reflux

My 1 month old was diagnosed with reflux last week. the doctor said to have his bed at a 30° angle when he sleeps to try to keep everything down. propping up the bed scares me since he's starting to roll around, so I've been keeping him in his bouncer at night. now I'm worried about hindering his hip development from him not being completely flat. I know there's angled pillows, but those seem too squishy to be safe. How the hell am I supposed to safely prop him up?!