My 3 month old is 50% height but 80% weight. does this mean i'm feeding her too much?

Mgt: As long as she is healthy, feeding well without diarrhea or vomiting, she can feed on demand. If you are overfeeding some signs include frequent spit ups.

Not necessarily: I find these numbers in the first 3 years more a simple set of parameters that help focus on growth.It is rare to have any kid with identical ht/wt/head size parameters. I don't find what you mention means anything more than baby is not underweight.