Arghh, I just came across your question, and I have trying to find the name of this book for 15 years, you described it absolutely perfectly. I read it in 1999, so it was definitely written before then. All of the answers people have given to your question this far are wrong, it's none of those books. I remember the hardback cover having a picture of a child in a spacesuit, which is why I picked up the book in the first place, as a nerdy nine year old. For some reason I thought the word "egg" is in the title, but I'm starting to doubt that. If I find out, I will come back to post.

Edit: okay, figured it out, and now I realize why I thought 'egg' was in the title. It's called [Star Hatchling by Margaret Bechard][1]

[![Star Hatchling Cover Image][2]][2]

I found the answer on this other stack exchange thread: https://scifi.stackexchange.com/questions/54844/sci-fi-story-told-from-the-aliens-point-of-view


  [1]: http://www.isfdb.org/cgi-bin/title.cgi?9454
  [2]: https://i.sstatic.net/SHPcz.jpg