Below 2 months, not all babies will have heavy pattern of drinking milk. It is okay if it is inconsistent. They still trying to adapt the proper milk intake. As long as they dont lose weight at every check up, meaning baby doing okay. For me, I get worried too because my second child dont latch alot unless she's really hungry for milk. That being said she will constantly spat alot of milk. But, it is normal because she gain weight from her last check.
Also, baby still trying to also adapt outside world and gets sleepy easily so don't overfeed nor underfeed. Try to see your baby sleeping/waking up time to adapt to feeding pattern.