3.5 weeks post tummy tuck - how can I tell if I ruined my results?

If it’s generalized soreness then it may be okay. However, to confirm you should speak with your surgeon since they’re familiar with the specifics of your situation.

The best advice will be that of the PS who performed your TT.  Many PSs will recommend 4 to 6 weeks before resuming strenuous activity with a limit of 10 -15 pounds for lifting. You want to protect your tummy from trauma that may be caused by swinging arms and legs and quick, jerky movements.  Proper lifting techniques can be applied to lessen the probability of injury or suture tension.  If you continue to experience pain or it becomes excruciating, check with your PS.
Kenneth Hughes, MD, Board Certified Plastic Surgeon
Los Angeles, CA

It's unlikely that you've done permanent damage but you may have set yourself back a bit in healing. I encourage you to rest and contact your surgeon for an evaluation if your soreness doesn't improve. It's always best to closely follow your surgeon's instructions for optimal results.

It's doubtful that you would tear any sutures and not have a sudden pain while carrying your child. Your plastic surgeon can test the strength of the repair at your next visit. Muscular pain is common and not necessarily caused by tearing sutures. Hope that is helpful.