Hi,
right, it needs sometimes some time for the milk to drop, up to 48h , most important is that the doe is not stressed, quiet and privacy is what they need.
Did you move the nest or is it in the place where she built it? Rabbits don't recognise their young by smell or whatever (makes it easy to foster kits), most important is location, kits that are where they built the nest are theirs. Ones that get out of there are out of luck.
I had to move nests now and then, from a earth hole in the garden to the hutch, I confined the doe to a space with the nestbox in one corner, just big enough for litter box, food and water, and to stretch out for about 3 days. Alone (I keep all my rabbits in pairs). I also dunked her nose into the nest several times, for a few seconds, so she could feel them wriggling.
Nipple number is irrelevant, my does have litters up to 14 kits, no problem. If you notice that some kits don't get fed, others well, you can take out the plumper 1/3 of the litter (keep it well insulated and warm) out every 3rd feeding, so the others have a better chance at the milk buffet. Normally one or two full bellies really make a difference. You could hold the doe and feed weak kits on her, but there are risks (tried it once, ended up with two fataly injured kits because the doe kicked out)
You can add plain kitchen oatmeal to her diet, about a tbsp twice per day, but a litter of 7 isn't that large, but nursing does don't get fat anyway.