Can weight lifting ruin my implants or cause negative effects on them?

If you're more than a year out from your breast augmentation, chest exercises shouldn't have a negative effect on your implants.  The pockets should be well-formed at this point in time.  Having implants placed under the muscle may lengthen the recovery process but you should be able to achieve close to baseline levels.  I would see your plastic surgeon to make sure the awkward feeling that you are experiencing isn't for another reason. 

When you are healing from implant surgery, every surgeon should have a protocol to take into consideration exercise routines and the timing of healing.  After a year, the position of your implant is pretty stable and the animation of your implant as it sits under part of the muscle can look "awkward" however that is a normal side effect of your implant position.  Best Wishes!!

Weight lifting should have no untoward effect on your implants. If your implants are under the muscle you may see animation issues as you flex the pecs.