Check out a local sling library you can try some out and even hire them if you want to. Definitely get one that has really good support for your back
We have the mamaruga zen which is a cross back adjustable sling - we tried it first from our sling library and then brought. I know the ergo baby is very popular too!
I like zoberlo. https://www.zoberloco.com/discount/AMALIA29237