We used a koala cuddle band at 3 months but it might not last too long as baby gets bigger. Our Tula FTG gets daily use and no complaints x
I used a boba wrap. We got a free one in our baby box in Scotland. Not branded but pretty much the same thing. Was great for our little one.
What sort of thing were you looking at? At 3 months old I would use a stretchy wrap, close caboo or ergobaby embrace. She's likely not big enough for a more structured carrier unless it's a from birth like Tula free to grow. Personally I would go to a sling library and see what suits you and your body type, as they're like a good pair of jeans - what suits someone else might not suit you!
I second the sling library, they will be able to do a fit check for you and baby and you can often borrow or rent a sling to try it out properly
I use a ring sling from hipbabywrap!
Do you mean you want a toddler carrier for your 3 month old or am I misreading? If so, they won’t fit unfortunately they have a minimum weight/size requirement. If you’re after a carrier suitable for a 3 month old I can recommend a few! X