Timing feeds for a 3 month old

I need help on timing feeds. My baby will indefinitely sit on my boob. She will feed, chill, feed, chill, feed, sleep, attached the entire time. I truly believe if I let her she would spend 24hrs attached. She has been like this since day 1. She goes against all the expert advice of ‘never un latch the baby. They will come off when they fall asleep for they are full’. Every infant feeding support person has told me not to unlatch because she’ll be getting hind milk. Anyway, the coming off on their own simply isn’t the case for my baby. I have a toddler and this isn’t sustainable at all. My husband has not been able to go back to work properly because of this. He does the odd few hours here and there when the toddler is asleep. My left boob is a major slacker, I always start on that one and she seems to take what she can then just comfort sucks or falls asleep, so I then move her to the right and she starts sucking and milk flow perks her up and she’s wide eyed and enthusiastic. Latch has been assessed and is fine, no pain, nappy output good, weight following her centile.

How long do your 3 month olds take to feed? It’s making me want to pack it in because there’s been no improvement and I can’t take it any longer. Don’t get me started on sleep, I’ve literally not washed my hair since last year because she needs my boob to sleep or for me to walk up and down the corridor with her in the carrier. She’s either feeding off me or sleeping.

It would be interesting to see what the average feed time is for a 3 month old because say someone says it’s max 30 mins then I’ll just time them.