Charlie first did a real smile when we was 4 weeks old. He's now almost 7 weeks old and has only smiled maybe 3 times since. I'm a bit worried because he doesn't make much eye contact at all but i've had his eye sight checked and it's fine. I hate comparing but Lily was smiles heaps all the time from the first time she smiled(at 4 weeks). Is this normal for bub not to smile at all?