My dd was a very late talker, to the point where I was asked if I wanted speech therapy for her (I think she was about your dd's age).
I'm a primary school teacher, was teaching Reception at the time (first year of school in UK), had training in language development, knew that children develop at different rates and that understanding is the most important thing but still had many moments of panic. I think that's natural, especially when it's your first child.
Like your dd, mine used baby signing and pointing, and clearly understood a lot. That was all that really mattered.
I can't remember when she finally started talking (she's 18 now so it's all a bit hazy). She was definitely talking fluently (full sentences, clear speech, good vocabulary) by the time that she started school.
I think your dd sounds a bright little girl and you're doing a great job. Try to relax and just enjoy this stage. It's a cliche but they really do grow up so fast.
Keep talking to her (but don't try to get her to copy you, aim for more natural talk and you responding to her actions and gestures), sharing books, singing, nursery rhymes. She'll get there when she's ready.