K.R.
Hey M.! It sounds like you have 2 complete blessings in your life! I used to work in the NICU. Considering your little angle was 4 weeks early, her adjusted age is just 5 weeks old! At five weeks, babies can, should & will sleep the majority of the day. Especially considering she is just recovering from RSV. Just like adults, babies need sleep to help them recuperate. A wonderful thing to do - especially since she was a premie - is to get her on a schedule. Every 3-4 hours (for now), wake her up, change her diaper, feed her, play with her (wake time), then put her down for another nap. There is no magic time to spend on each thing...but the gist is sleep time, meal time, wake time, sleep time... Try to keep her up playing for at least 30 minutes after she eats & as she grows, you can extend the time.
It is wonderful to have children who sleep well - all 3 of our children 1, 3 & 4 still take a 2-3 hour nap in the afternoon & sleep 12 hours at night! I pray the same for you & your family. Blessings!