My baby also 3mth old now. Its normal for them to have longer sleep at night now and but only 2-3 time naps at day. As per my reading baby started to develop sleep routine at this point, like my baby will wake up around 2 am and 5 am for feeding at night and random feeding during daytime (i guess prior to how much his exercise n playtime exhaustion haha). Anyway just monitor his weight and enough wet diapers imo