I have 6: DS 16 and DDs 14, 10, 6, 5, 5 (twins) so there are only 15 months between the twins and DD3.
We only planned 4 but I love having 6 kids! They key is planning, but even then it's mostly chaos with 1000000 people trying to get your attention or at least that's what it feels like.
I can't comment myself as we jumped from to 6, but the two other people I know with 6+ kids say 6 doesn't feel that different to 5. But then again, since you've got a bigger age gap, I guess you will be jumping back to the baby years again so it will feel quite different.
It is good when the older ones can help out too. My oldest was 11 when the twins were born and even little things like rocking the crying baby when mummy has her hands full are important, plus they can do more chores.
Try and include your youngest in 'big sis' jobs like looking after the baby (not alone obviously) to make her feel important but don't forget she will want babying sometimes too. A little bit of rivalry/jealousy doesn't kill.
That's a lot of c-sections! I'm sure you are in the best hands though. I had 3 VBs followed by an emcs and an elcs and they were the toughest, but you must be an old hand!
Anyway, you're not very far in yet so focus on yourself and your pregnancy for now. You can worry about the rest later!
Good luck! Happy to answer any more questions