@Naomi353 There is no way to know why dates are blocked or open on a calendar. I have had guests who showed they had been members for years, yet had no reviews on their profiles. There were perfectly legitimate reasons for this and they were all great guests.
Also not all hosts or guests bother to leave reviews, so she could already have hosted a couple of guests who didn't review.
What is a bigger red flag is a host who doesn't respond to your messages. So give her a bit of time to answer, if you don't get a message back, try texting to her phone number that you've sent her an Airbnb message and to please answer. Airbnb is rife with tech glitches and there have been many posts here over time where either hosts or guests said that messages they sent were not going through.
Sometimes someone can be where they have no cell or internet reception, or as with one of my guests who wasn't answering, who was at a meditation retreat where they weren't allowed to use any devices. Someone could be ill or have some other crisis going on in their lives that prevents them from answering right away.
We tend to assume that the other party is simply ignoring our messages, but that's not always the case. And if you can't get an answer from her, you can ask Airbnb to try to reach her.