Hi Alyssa's Mum,
You poor thing. I have only experienced a few nights of such little sleep as you are experiencing and it is hell and leaves you incredibly teary. How you are standing up is beyond me. I've only got a couple of suggestions that may put your mind at ease.
I have an Angelcare monitor. They can be bought from Target or baby stores. It is just like an ordinary monitor but also has a sensor pad which is placed under the baby's matress. If there is no movement for 20 seconds it will alarm. I use it every single time my baby goes down for a sleep, day or night and have peace of mind that if anything should happen I will be alerted. Several of the other Mum's in my mother's group have one and we all agree it is a god send. You know it is working because if you take bub out of their cot and forget to switch it off it will alarm after 20 seconds. How it can measure their breathing through an entire cot matress is beyond me but it does and it is brilliant. None of us have ever had a malfunction so I highly recommend it to put your mind at ease about Alyssa's wellbeing. Knowing she is safe may help you to relax. They are $170 at Target - I got mine on special for $109.
Also, if you are worried about her choking on vomit I have chosen to sleep my baby on her side. Mostly because she seemed to prefer it this way. I know it is against SIDS advice, however, I purchased a bumper from BigW which goes either side of her and prevents her from rolling forward or backward. You may wish to try this if choking is a concern for you. Even though it is not the preferred SIDS back sleeping I feel okay knowing she can't roll and the monitor will alarm if there's any problem.
As for you I can only suggest trying to switch that mind off. You need to have bub far enough away that you can't hear every murmur, just when she's serious and needs you. My DD makes heaps of noise in her sleep so sleeps in her own room. I can hear her when she calls out or cries but not when she is stirring or dreaming. Have a nice warm shower or bath before bed, try a lavendar oil or cream, relax your shoulders (you'll probably find they're up around your hears), try and think of nothing - focus on black nothingness and if need be count back from one hundred (sounds crazy I know). Works for me most of the time. Or if you have a partner, ask him to rub your hair or back to help you drift off. Don't lie awake thinking she will be up soon for another feed. She'll wake you when she's ready so don't pre-empt it.
Let your mind switch off. She will be okay and you are doing a fabulous job as a new Mum. And if there's anyone that can give you some help ie. Mum, DH or friend so you can catch some sleep during the day, don't be afraid to ask for Help.
If you're having trouble with a routine, I started by figuring out how long bub was happy to be awake for. Around 11 weeks it was 1 1/2 hours for her and she was feeding 3 hourly. So I'd have her up for 1 1/2 hours and then asleep for 1 1/2 hours. Feed, play, sleep. She always stirs after a 40 minute sleep cycle so I re-settle her, knowing she needs to sleep through to her next feed. My sleep book says only one sleep cycle, or less than an hour is not a healthy sleep. Once you get some sort of feed, play, sleep routine going throughout the day, all else I can suggest is feeding more frequently in the evening (say 2 hourly) and giving bub a bath, followed by a lavendar cream massage to relax before bed and trigger her big sleep. Has worked for us so far. As for settling - wrapping tightly and a dummy settles my little one.
If you need any support or someone to chat to PM me.
I wish you luck in getting a good nights sleep. See your Doctor if things don't improve. You need to take care of yourself in order to take care of your beautiful baby.
Thinking of you.