Oh, yeah. That's a bit of a weak point in frames like that. Without seatstays behind the seatcluster the seatcluster is a major failure point, especially when you're rockin a massive setback seatpost.

Your seatpost has what, 3" setback? That's kinda bad.

I suggest getting a frame size one notch larger and a zero setback seatpost.

The current configuration with the massive setback seatpost puts WAY TOO MUCH stress on the seat cluster.

Replace frame with one that can work for you with a seatpost with little or no setback.