How do I know when baby is actually hungry

[SunnyRoseSloth]

Baby is 17 weeks old and is exclusively breastfed. We did give her a bottle in the early days but I got lazy with pumping and just decided to feed her myself.
Now I just feed her about 20 minutes after she wakes from naps, whenever she wakes in the night and when she is narky so I'm not really sure what her hunger cues are. When I do feed her throughout the day, she tends to spit a lot of it back up so I'm definitely over feeding.
I'm attempting to teach her to sign when she needs milk but that will obviously take time but I need her to take a bottle so I can spend a bit more 1 to 1 time with my oldest and go on a night away with my husband that was planned and booked before she was born.
Does anyone have any advice please.

Usually a clenched fist and "rooting" are ques of a hungry baby. Sign language can be really helpful and something I taught all my babies but as you said can take time.

You’re not over feeding her-some babies spit up more than others. Just feed her whenever she asks-it will sort itself out. So long as she is putting on weight steadily and lots of nappies!

Some babies are just sicky, it doesn't mean you're over feeding.

It in doubt whip em out was my feeding motto.

Breastfed babies general feed often. Signs will be turning head left to right, rooting around, sucking hands, closed fists.

Here is a link with some images of feeding clothes https://www.breastfeeding.asn.au/resources/feeding-cues