Exceeding recommended daily protein intake

Its not harmful unless you have pre-existing kidney disease (for these people you actually want to restrict protein). But your doc would let you know if that was a concern. You're body will increase oxidation of protein if supply is greater than needs to take care of it.

Not likely that a high protein intake would be the culprit for slowed weight loss. It usually helps if anything. Some common things that may slow weight loss: 1) a caloric intake <80% of your TEE. 2) loss of lean body mass resulting in lowering of metabolic rate (why weight training is helpful for weight loss).