There is beauty where you are, you might not be ready to see it. The difficult trick is to stop comparing. You need friends. And also, don't be so focused on the Swedish connection. You have it at school, know a few people. Great. But there is more.
Spring is here, and Spring in France and Paris is gorgeous. Focus on what attracted you there.
Everyone constantly tells me how great my life is, with so many countries we have lived in. What they will never understand is the number of goodbyes we make every time we move, and for many friends, it is an adieu, I am never going to see them ever again. And in addition to the people, we get to love places, be it a café, a bookshop or even a square. We have memories connected to places. Events that brought us joy.
I think you are a bit in the grieving phase, missing what you had. It is normal.
You made the right choice in picking a Swedish section. It is astonishing the speed at which a kid forgets a language even after having lived in that country for years. And for the languages that belong to the household, unless you do homework, writing in both, one will always be stronger .
The life of an expat being bounced around isn't always as glamorous as it looks. Where is the forever home my kids and grandkids (don't have them yet!) will come back to, a house filled with memories, old toys, old books, summer holidays ?
You didn't feel like Sweden could be the forever-life for you, and I get it, at some point, we want to go back to our roots. For you, it is France. You just need to make yourself at home in a new city.