Agree with the rest that there is no need to fret. Babies typically wake up at the end of each sleep cycle and it seems like your baby is capable of soothing himself/herself back to sleep (or with minimal help from you).
As long as your baby is still gaining weight, he/she is getting enough milk. Also, baby would definitely cry to let you know that they are hungry or not getting enough. Especially when they are still young, they tend to be driven by their needs and keeping themselves full is one of the basic need that they would fulfill.
On the whole, just react according to what your baby is "telling" you. Take care mummy! Remember to drink lots of water and maintain a balanced and healthy diet since you are breastfeeding. Also, get as much rest as you can. :)
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