I agree with all the other posters--don't worry about baby getting enough playtime or stimulation for now. Being held, in your arms, hearing your voice, nursing--that is what baby needs at 7 weeks. I noticed you said your baby seems to have less 'quite alert' time than other babies and that you're struggling with his weight gain due to poor milk transfer issues. The only thing I would say is, regardless of how you go about it, it is very important during this time to make sure baby is getting enough to eat. Sometimes overly sleepy babies are babies who are not getting enough food. Sometimes, they are just sleepy babies. However, if his weight gain isn't good, then that combined with his lack of much happy alert time could be concerning. You should talk to your pediatrician and figure out if your son's weight gain is adequate and if not, how to fix that. If that means you need to supplement in addition to nursing, either with pumped breast milk or formula, then so be it. Getting enough to eat is crucial to his brain development right now. HOWEVER, breastfeeding itself is in no way harmful to your LO's development and is only helpful as long as he is getting enough milk. There are multiple studies that show breastfed babies tend to have a slightly higher IQ than formula fed babies. Whether this is a real effect or has to do with other factors, such as more educated moms being more likely to breastfeed, isn't entirely clear but it appears that if anything, breastfeeding is BENEFICIAL for babies' cognitive development.