Sorry to pile on, but yeah, you are basically riding solo. The problem with dangling off the back of the pack is the riders in front of you are not going to be very predictable and confidence inspiring, which prevents you from getting right up on their wheels, so it becomes a bad feedback loop. If you can get yourself right into the pack, wheels will be more predictable and easier to follow.

Spend some mental concentration to save a lot of physical effort. If you are in the right situation on the right wheel, you can get literally inches off that wheel and you just get sucked right along. It takes a lot of focus though.