hi dr..i used to burp.my baby by placing him on my body(against his tummy)..i use pillows backside to support myself. i lie down little...and he sleeps on his tummy upon my shoulder..(his head on my shoulder).. he sleep peacefully over my body ...is this tummy time..as he is 3 mnths old and he lifts his head while bwing in this position.. i rub his back and make him relax.. is this position safe for baby to sleep???