Oh wow, how on earth did more than one idiot tell you to look for signs that she is hungry, instead of waiting for her to communicate with you in the way that babies communicate - crying!
If during the day it goes longer than about 3 hours before a very young (4 weeks is still very young), and entirely breastfed baby, tells you they are hungry - by crying - then you could look out for signals like them looking for a nipple. My darling Grandson tried to find one on my arm, so his mum and I laughed, and I gave him back to his mum. They also might try to put their little fists up to their mouths, but once it gets past a little tummy rumble they will soon start crying to let you know.
Of course, as crying is how they communicate, that crying will be telling you that something, anything, is not quite right with their world, but that is completely normal. It can take quite a while, especially if you are a new and first-time mum, to start to notice any differences in your baby's cry, and to be fair, it takes the little scraps a while to develope a slightly differently nuanced cry for their different wants and needs. So to begin with, a slightly cold, wet or pooey nappy, or wanting feeding, are usually the main reasons for crying. But wanting cuddles, the warmth and heartbeat of a parent, and the secure arms, and the soothing voice of someone who loves them, is often what they want at any particular time. So after checking their nappies, and if they simply cannot be hungry -but they can, they are growing so quickly, and particularly if they are breastfeeding, it can be hard to know for certain that they took enough milk! But please try not to worry too much about that, as long as you offer them the breast, and they are being weighed regularly by a nurse or health visitor, they should be fine.
So check nappy quickly when they first cry, then offer them their milk, and if it isn't either of those two things, then they might be a little chilly, or have wind, but they probably want a cuddle, and as they spend more time awake, they could be bored as well, which is where maybe letting them watch a little bit of TV starts, if there is no-one available at that precise time to give them the attention they want. Each mum, or baby's primary carer, will develope their own routines, and hopefully between mum and baby they develope one that suits the two of them the best.
For me, once I had checked their nappy quickly, and if it seemed reasonable, I gave mine one breast straight away so that they didn't get too upset with their crying, and then changed their nappy (which helped my babies, as otherwise they would usually fall asleep after one breast, sleep for about half an hour or 40 minutes, then wake up again wanting the other breast, Lol) before putting them on to my other breast, as, like I intimated before, changing their nappy would almost always wake them up enough to have a good empty of my second breast. Probably everyone does this anyway, but I would always start a breastfeefing session on the opposite breast to the last time, to try to ensure that every second feed each of the breasts have been fully emptied.
So please do not keep on waking up to see if your beautiful little girl needs feeding, she will almost certainly do the completely normal and healthy thing, of waking you up by crying, when she is hungry. Of course, I don't think anyone can suggest a way to stop new mums from waking up to check that baby is still breathing, I think that is probably built into our DNA, but as baby gets older, and mum gets more confident, the waking up to check on baby does get less frequent - but I think that the tendancy for mums to do that is one of the great reasons for keeping baby in a cot or crib, right beside them, for about the first 6 months. It also hopefully means that when you do your instinctual half waking up to check baby is ok, you can check really quickly, and then get straight back to sleep.
It sounds to me @Becka14587 that you are doing brilliantly, but please do try to get it out of your head that you should catch when your baby is hungry, before they let you know themselves. Of course people who have very premature babies, or babies who are otherwise unwell in some way, may be given different advice, and if that is the case then the mum should absolutely follow the paediatricians advice. I am sending you a big hug OP, if you don't want it, just wave it away xx