This is my name, a not uncommon Latvian girls' name. In Latvian it is pronounced Uh-Stra (Uh- as in 'putt', and with a rolled 'r'). In English my name is pronounce Au-stra (Au- as in Australia).
I love this name for the long 'ah' vowels in it - they give me an impression of regality and grandeur, or (if you *want* - but I disagree with what I'm about to type) glamour.
I think Astra is very feminine and I like the meaning. I once played with names and I came up with Azharastra. Azhar means "bright" and Astra means "star". I think this would be a good name for a female heroine in a story.