Can I carry my own pillow on plane?
since I’ll be traveling with a small baby and I breastfeed her but he only breastfeed while laying down and refuses to take while am sitting up.. the only way she drinks milk is if I have a pillow on my lap nd shes laying straight and The pillows on the plane are too small for her, so can i carry my own pillow since we wont drink milk otherwise?

Honestly, I think a pillow will be too big unless you can somehow get one inside your extra bag (not the carry on, but whatever you use as a purse/baby-bag). I’m just going to be completely honest with you and say that I would not be comfortable with a woman breastfeeding on a flight and it would probably be easier to use a bottle of your breast milk. I’m not the kind of person that would say, "Oh, gross!" but I would feel like my boundaries were being violated, and in such a small area like a plane, if I was sitting next to you, I would be highly uncomfortable. I know that’s not what you asked, but that’s just my perspective.
Good luck on whatever you choose to do!
Yes you can take your pillow. Try and fit it inside of one of your carry ons though, at least squeeze it in long enough to walk on to the plane, so you don’t have it counted as one of your two allowed carry ons.
You can take your own pillow with you; however, keep in mind that the airline is likely to count that pillow against your carry-on limit. (In the US, airlines typically allow one carry-on bag plus one small personal item, such as a laptop, purse, or small backpack — the pillow would be counted as your personal item.)
If you intend on using all of your carry-on allowance, you’d need to find a way to place the pillow inside your other bags; otherwise, the airline would likely require you to gate check your larger bag in order for you to take your pillow onboard.