I bought a 2nd potty for upstairs today and my 3.5yr old DS who we are in the early stages of toilet training. problem is he can't actually fit his willy in it between his legs when he sits down! I seems it is just too small (his willy really isn't that big!). Has anyone else experienced this and can advise on what make/brand to buy? The other one we have is ok (Thomas Tank, seat style) but was just looking for something a bit smaller overall but with a bigger 'opening' x