One of my children also suffered with reflux- Infacare make a special formula that you mix and give immediately - it's thicker than normal foruma and designed specifically to keep the food down... worked a like a dream.
Also my other child didn't enjoy sleeping on her sides (I don't do sleeping on the back at such a young age), she did however roll over on her stomach and that's how she slept for weeks... scary but we all slept very happily...