Advanced Language for a 16 Month Old Toddler

At (almost) 16 months my daughter has over 300 words (I've lost count) and is regularly using 3 words together and sometimes 4. She uses nouns, verbs, adjectives, adverbs, prepositions, pronouns (just I and you at this stage)...but not conjunctions or question words.

She has just started using s on the end of words to make plurals- although she's not always quite right. She is also developing a sense of humor - one example, she tells my dad a deer figurine at his house is a dog and will argue no matter how many times he says it's a deer- then the moment he leaves the room she laughs, looks at me and says "deer". This is a long standing joke of hers- going on for almost 3 months now.

She can follow 2 step instructions. She asks me to read her books. She can sit through fairly long stories and seems to understand the majority of what she hears. Yesterday she listened to a book (with no pictures) being read to her older cousin and made her own comments on the story.

Strangers at the park have commented to me a few times that she is very clear (in her speech), and I find most people are able to understand around 3/4 of what she says. She doesn't use all letter sounds properly and certainly has unique pronunciations of some words.

I have been looking on the internet to find out the range of language development for her age. Most charts I have found are showing the upper range for 18 months to be 50 words plus and she's only 16 months. We do lots of social activities and haven't found that other kids her age are at her level. Is it really out of the ordinary for a 16 month old to be using language like this?

How can I support her language development without alienating her from her age peers? She already plays better with 2 year olds than kids her own age and I'm worried that she is going to have social issues later on at school.

Do SLPs work with kids with advanced language, if that's how her language would be described?