Switching to bottles... disaster

Hi
Our girl is now 11 weeks old and we are starting to wean off breastfeeding because my milk supply turned out to be insufficient over the last 2 weeks. She wasn't gaining enough weight according to the pediatrician, and when I told him she was latched on for hours... the picture didn't add up. She's not nursing efficiently (probably also due to tiredness, poor latch... although two midwives came to check and said it was fine... thanks to the professionals!)

A lactation consultant came to see us and gave tips on how to wean... easier said than done. I won't be able to save my supply, otherwise I'd be completely burned out... my husband is now helping out too...

I feel very insecure, emotionally also because of weaning...
I feel very guilty towards my baby for stopping the bf and have the feeling that I'm taking 'something' away from her. Namely the breast, comfort, security...
I got a plan from the LC to wean, but I find that I can't manage it. My little one doesn't sleep during the day... either in the sling or we're lucky and she sleeps for 45 min before going back to screaming. She cries a lot, I suspect either from hunger or tiredness (I can't tell the difference) so pumping at set times doesn't work for me... herbal tea alone probably won't help?
I no longer give 'live' bf's, since my production was too low and I don't know how much she's getting.
So we've started with bottles of Nan. According to the box, she should get 5 times 150ml and at 12 weeks this should increase to 180ml.
Now I was wondering when I should give these bottles? How much time should be between them? How do I see if she's hungry? Before she was almost constantly at the breast, so yes...
Are those 5 bottles counted for daytime, excluding night feeds, since she comes for a night feed at 3am or earlier or later.
Until last night I still gave her the breast, but I don't want to continue doing that because I don't know how much I still have (...)

This morning she woke up at 7am and I gave her a Nan bottle. She then slept until 10am. Normally I should pump (every 6 hours now) but since she was awake I latched her on and then offered a bottle afterwards. She drank 30ml of that and then fell asleep for 45 min.
At 1:30pm I offered another bottle but she only drank 100ml of that, then fell asleep. Once in her crib she wakes up after a few minutes... exhausting. Also constantly crying, yawning... I don't know anymore.
Now she's in the sling and 'dozing' there, but I have to keep rocking!
So I'm not getting into a 'schedule'...
Would appreciate some help with this, because I can't ask my husband either because he doesn't know anymore either...

I read Ria Blom's book and she recommends working with a structure. E.g. wake up at 7am, feed, cuddle, change, play and solo play and then put her awake in bed. Let her cry for the first 2 days (max 20 min) and this should improve afterwards...
Normally babies should be able to sleep 1h30 to 2h after feeding. This pattern would then repeat at 11am, 3pm, 7pm and then the last feed at 11pm. At 11+3 she should fall asleep afterwards and after the 7pm feed she should stay asleep and you have to wake her for the last feed at 11pm. Afterwards on demand at night?
I don't want it to be that strict now, but I do want her to eat enough and sleep enough. Now she cries a lot... yawning, fussing,...
We've never let her cry for long, we always pick her up, carry her around, rock, sing... we basically have no moment of rest. The moment you think she's sleeping and you want to hang up the laundry, she's already awake...

Would appreciate tips from others on how I can make this a bit easier for both my daughter and me.
I feel so insecure, don't know why she cries,... pffh difficult...and if I cry about it too, then it's really super fun here...not so
I'm afraid something is wrong, but my husband says I'm seeing ghosts.