You said you had back problems, so I'd be inclined to use wraps or structured carriers that distribute weight evenly across your shoulders and hips. I'd avoid anything that is one-sided or hip carries. My osteopath kept telling me off because I'd carry Sparrow on one side only & it was taking my pelvis out of alignment.

Woven wraps (not stretchy) are great. Don't be intimidated by them, because they're really not that complicated once you use one. They offer great support and hold baby snug and closely, which is good for your back.

A soft structured carrier like a MaiTai may be really suitable. I've not used one, but many of them look so comfy and snug. They have less bulk (and are usually better for hotter weather) than more structured carriers like Ergos.

See if you find a local baby wearing group to try a few different wraps & carriers.