No, it doesn't mean they are in Bespin's system. You are think too much about actual distances and our inability here to travel between them.
No.. imagine they are in a car. Anoat (where they are when they are clamped to the star destroyer) is in upstate New york. Hoth is located in Pennsylvania and Bespin in in Florida.
Considering that georgraphy, I could drive to Anoat from Hoth and I could even drive to Bespin.. but that trip would be a bit mire exhausting and it would take a while. If I had a plane ticket (hyperdrive) then the trip to Bespine would take two hours, but I wouldn't need that plane ticket to get Anoat from Hoth.
Star Wars ships go between systems like we can use a car to between towns.. because Star Wars is a fantasy.
If they could travel between systems as you suggest why go to Bespin at all? Why not just meet up with the Rebel fleet?
I odn't mean this is an insulting way, but but there is no evidence that the fleet assembled in any substantial way until the end of the film.. actually that shot isn't even as extensive as we see it at the beginning of the enxt film when the fleet was actually "assembled."
Taht being saud.. to continue my analogy, the Rebel fleet could be located in France, in which case my hyperdrive or plane ticket, would be necessary regardless. Call it that mass in the center of the galaxy, or a lot of foul systems that the Falcon would meet along the way that they could skip over easily witha working hyperdrive.
It's just important to know, when watching Sta rWars, is that using a whole lot of science isn't a good idea. The science of outer space doesn't apply, but I do generally use earth-bound physics basics when thinking about it.. like the fact that R@-D@ is a niche in the back of the X-Wing is enough to confvince me that he won't fly out, but I have a problem with droids rolling around on the surface of the ship as it is moving forward in The Phantom Menace... I also have a problem with them travelling through the planet's core in that movie. But in general, the distances between systems should not be equated with what hwe know from actual science.