I know it's easy to say but hard to do, but... don't worry! A week from now you are going to meet your precious baby and all of this anxiety will melt away. <3
I was planning an all-natural hypnobirth, and my OB was completely supportive. But when DS was breech (and nothing I did could get him turned), we both decided a C-section would be the best option for me. (Upside- she thinks I'm a great candidate for a VBAC next time.) Hopefully you feel very comfortable with your OB -- that's the first most important thing. I had such anxiety about scheduling my C-section also, but once I finally accepted it and placed my trust in my OB, I felt at least a little better. I also talked through all my wishes with her, and she met every single one of them.
So think through your birth plan wishes and share them with your OB. For example- I was terrified of the OR (had already had several abdominal surgeries in the past & some PTSD from them). So I asked that they turn off all the sound on the beeping machines -- and they said no problem- they didn't need to hear any of the beeps. It made a HUGE difference. Also, they had on the radio & asked if there was anything in particular I wanted to listen to.
Another help-- I didn't want to be separated from the baby for any more than was absolutely necessary. So they brought DS over to me (after clearing his breathing & cleaning the poop off him -- first thing he did was poop on my OB, lol) and he was able to lay on my shoulder/neck/chest for the entire rest of the surgery while they sewed me up. He only left moments before I left the OR. And that made the BIGGEST difference! I was so nervous I was shaking horribly at the beginning of the surgery, but the baby is actually born very quickly (focus on that!) - and as soon as I heard him cry, I was able to refocus on that, and as soon as he was with me - touching me & DH - that was my focus, and really my memories of the entire rest of the time were of that bonding experience and of taking pictures of all of us for the rest of the 40 minutes or so.
A tip-- they cauterize you as they go along, and it smells...horrendous...if you've never smelled burning flesh before, there's really no way to describe it. But the anesthesia tech opened up some alcohol wipes and held them under my nose (or maybe it was DH who held them, I forget) and that took care of getting rid of the smell.
If you know anything about meditation, relaxation, visualization - I highly recommend using those to help calm your nerves and get you through what you are feeling. I found all my hypnobirth training helped me, even with this opposite type of birth -- being able to breathe myself into a peaceful place.
I think everybody else covered all the other important stuff- staying on top of meds, getting up and moving asap, etc.
But I strongly recommend thinking through what you want for this experience-- that will give you some bits of control. (There are tons of sample C-section birth plans online.) And hopefully your doc / hospital team can help you get as much of what you want as possible.
Best of luck & congratulations!
PS- one last tip that I got from my doula (who was also a great help- they let her in with my DH for the whole thing, and then she was able to stay with me while DH went with DS to the nursery for some tests briefly after birth)-- hormones change in a HUGE way once your milk comes in (about 3 days after), and for lots of women it can be a bit of a tailspin. So if you feel you start having more of a hard time at that point, just know that it is temporary and that there's a great biological reason for it-- your body is changing to a lactating woman. But it will pass. (I started crying hysterically and frequently -- many times a day -- and it lasted for over a week, maybe 2...but it definitely passed.
)
PPS- Everyone told me to be aware that I would feel pressure and tugging, so I knew that going in. But what I didn't understand was how intense that could be. I thought it would be general sensations in the surrounding areas, but I really felt like I could feel a lot of it in the actual locations they were pulling/tugging...BUT don't worry-- there is NO pain from it. So don't be scared if you feel a lot of strange sensations- they will make sure you're not feeling any pain before they get started.
And finally (PPPS?), I'm somewhat pooh-sized, too. Have been slightly different sizes for each surgery I've had, but like some previous posters have said- the only thing I noticed that made a difference in recovery was when I got up sooner and moved around more (within reason) like I did with the C-section, I recovered MUCH faster.