I agree with @Norachan that you should continue giving the bottle for awhile longer. Kittens never stay on the bottle forever, but 5/6 weeks is on the young side and most kittens that age may be starting to wean but are also still nursing mama. Let it go, give the bottle for now and be patient...
It’s okay if the gains are less some days than others as long as they are not losing. Like human babies, they eat, gain, and can plateau here and there and maintain, then comes a new growth spurt and insatiable hunger. Since she’s not lethargic she sounds fine — just wasn’t overly hungry that...
The kitten is likely hungry. Put it to the mother cat to see if it will latch and nurse. If not, you may need to hand feed with kitten formula and a syringe. Here is a helpful video:
Syringe Feeding — Kitten Lady
You can also try stimulating its bottom gently with a warm, damp, soft cloth to...
Add 2-3 drops of olive oil to each feeding. This helps to make the poop easier to pass. You can use A&D ointment on her bottom while she’s this tiny and not cleaning herself. Coconut oil works well also and is non-toxic.
Checking temperature is not that helpful I’ve found. She’s close. She’ll have them when her body is ready no matter how many times you check her temperature.
I wonder if he has an infection and is trying to tell you he doesn’t feel well. It’s possible he picked up something when he was being neutered and needs meds to treat. I think talking with a different vet is a good idea.
She went in to see about her babies. Her teats were probably full and those mama hormones are very strong when the kittens are this young!
I’m sorry it took so much work, but it’s awesome that you persisted and now they are reunited, which is a best-case scenario. Do let us know what happens next!
It doesn’t look good. If she hasn’t passed the last placenta she may need a vet to give her a shot of oxytocin to stimulate contractions to expel any leftovers. She is at risk of infection if material is left inside.
How many kittens did she have?
I hate to say it, but a shy cat like this may take many more months to get completely comfortable with you. It’s going to be on his timetable and not yours, no matter what you do.
Since he accepts you when you come in the room to visit, and he’s comfortable roaming at night when it’s quiet, the...
No, that’s not likely, but she may take her time coming out to eat. Can you place her wet and dry food near where she is hiding, plus a bowl of water? The closer it is to her the easier for her to venture out. It may take a few weeks or even months for her to get comfortable, and even then, if...
She likely has swimmer’s syndrome and needs her legs taped for support while she is developing so that she gains strength in her tendons and can begin to develop more normally and use her legs properly. This needs to begin immediately. Here is a helpful link with videos from Kitten Lady...
A preemie this small cannot hold more than 0.5mL per hour. It will be a labor of love to keep this one going because you need to feed around the clock. The only alternative might be tube feeding, but this is very dangerous without proper training. Getting this kitten to 100 grams will be a...