DS2 turns 7 months next week. He is small for his age (just under 7 kg) and is a very wriggly, smiley baby. He feeds and sleeps well but has only rolled over a few times, shows no sign of crawling, pulling himself up or sitting up unaided. Looking back at photos of DS1, I've noticed that DS2 is doing a lot less and strangers are often surprised when I say what age he is because of his size. HV not concerned about size. I just wonder if there's anything I can do to encourage his gross motor skills. Thanks.