I was given my Moby when my son was 3 weeks old and we loved it! Now he's 3 months and much bigger at 15 pounds and we sometimes don't feel comfortable in it now. He's often to low or to high and we struggle to get the right fit sometimes. Also one of his little legs comes out and gets cold when we're out (I've since bought him tights so it's always covered) instead of staying inside the "seat belt" part I tuck it into. Is it time for a new carrier? Does Moby have a weight limit?