Hello dear
Warm  welcome to Healthcaremagic.com
I have evaluated your query in details  .
*  You are on perfect line of management  for  the  
gastritis  till waiting for    
biopsy of the rectosigmoid  polyp .
*  I  recommend  additional inputs  for  better  outcome  as  :
Prefer soft , light , bland , vegan diet till possible .
Consume more of whole grains , cereals , pulses , legumes , organic fresh fruits .
Avoid  all oily , spicy , non veg , hot beverages , junk foods , carbonated drinks .
Avoid over eating , prolong fasting .
Avoid resting upto 2 hours after meals .
Fix your timing of breakfast , lunch , dinner  till possible .
Have  regular walking in fresh air , exercises , 
YOGA .
Avoid 
smoking , alcohol if consuming .
Avoid 
stress , 
anxiety .
Manage  to have regular sound sleep of 8 hours .
Continue current medications  according  to the  advise of your doctor .
Keep your  BP , blood sugar , 
cholesterol , body  weight  under  control .
Hope this  will help  to clear your doubt   .
Wishing you fine recovery .
Always welcome for any further assistance anytime .
Regards  .