sling recs

Hey im just wondering if anybody uses a sling to carry there kids?? I dont mean the baby bjorns i mean the fabric ones that you can use til the child is about 3.
I had a baby bjorn when callum was little but he grew out of it quite quickly, i have recently seen ones one ebay that you can use til they are 3 and i was wondering if they are any good or are there any particular brands that are better. I mainly want it for carrying my son (17months) to daycare and back.
Also are they supportive? I am pregnant again so can you use them if you’ve got a big belly in the way? I seen a pic of a woman who was carrying her toddler on her back in one sling and a baby on her front in another one!! Surely to do that they must be supportive??