Sleep regression

Hi mummies! My LO is currently 3.5months old now and i notice she’s getting really fussier especially in the late afternoon onwards and she takes very short afternoon naps. Also, as for night routine, usually she’ll be able to sleep right after her milk, but now we will have to soothe her to sleep (rock, walk, you name it) or even use pacifier. However, she’ll still be able to sleep for about 6-8 hours every night. Is this sleep regression?