DS is 10 months and we've had the Nipper since birth and it's been great but now he is getting bigger (91st centile for weight) I can't get it to sit up enough for him so he doesn't slump to one side and the harness will only do up on one side on it's maximum settings. I had hoped it might last us till he was walking but it seems not. Is this a common problem? Was thinking about getting a Maclaren for use round the shops but do really need a good 3 wheeler as have 2 lively dogs to walk on muddy tracks.