Need advice on wet diapers/dry diapers

Amy • Married cat lady and mommy to Charlotte Rey 💖
My 3 mo old has started sleeping through the night, usually from like 11pm-6am. Well yesterday she was very fussy and needy and spit up ALL. DAY. LONG. Every time I turned around she was spitting up. Sometimes clear, sometimes milky, other times cottage cheese like. I typically feed 4-5 oz every 4 hr. I fed her 5oz at 6:30 pm and changed her diaper a little after 7. She played and fell asleep fussily at about 9. I knew she would be waking up soon to eat so I didn't wake her to change her. Guys. She did not wake up until 6 am. 😱 She woke up happy and ready to eat. But her diaper was only a little wet. Almost 12 hrs and I expected her diaper to be soaking! Not just a little wet. Well I changed her about 6:30 and fed her at 6:45. Just checked the diaper st 7:45 and still no pee.
Should I be worried? I mean, where is all the pee? Is she dehydrated? Her mouth is wet (she's drooling a lot actually), hasn't cried so I can't check tears, no sunken in spot. She has no fever.  But she did go right back to sleep after eating. Should I try something different? Offer her less to eat more often? I'm checking her diaper once an hour now. Any advice before I call the doctor? 😞