Breastfeeding with engorged breast

Ok i need all the help i can get im in excruciating pain my baby is rather small and my nipples are not so her latch hurts and on the 3rd day when my milk came in i became engorged i am pumping and rubbing and using a heating pad to help. But only a little progress. How long can i leave a heating pad on? And any advise on the latch the ratio of baby to nipple is not a good one lol