Severe heartburn at 32 weeks pregnant. HEEEEEEEEEEEEELP?

i am 32 weeks pregnant, and i have been having severe heartburn since 20wks. My doctor prescribed peptac which use to help at a point but now no. i sleep on a seating positiin with several pillows on my head, but with the seating position, i am nolonger on my side its like i am on my back, but seating, i don`t know if that is bad for the baby, but it seems to be the only way to get rid of the heartburn at night and i sleep, but i am worried cos when i get up, i find myself nolonger in a seating position, but almost lying down completely on my back, but still with all the pillows on my head so i am still probed up like i was using them hospital beds and having my head lifted up, but lying on my back, so i am not lying completely flat on my back, but i am still worried, is that safe or dangerouse for the baby, with all these things i hear about not advisable to sleep on ur back for it is bad for baby, i really need advice. thanks