Spot on, my conclusions on that:
The xenomorphs didnt grow faster than other xenos, at best they grew just as fast, I think mr H and his youtube channel started the claim that they somehow could grow faster which the movie dont show at all. Either due to the mutation they grew slower and was more affected by the host health status than normal xenos, or Purvis actually carried a queen which would explain why he took several days to have the chestburster ready to burst out, and then only due to the shot he got that triggered adrenaline rush.
And not here arent any male or female xenos, its at best a fan idea as some like that idea that they have to be like humans and mate and that created the newborn, I can see the logic of it but no. The queen reproduce asexualy and once her second set of ovaries started to work it produced a live embryo which caused her to stop lay eggs and started to grow a womb instead of an eggsack, she was still able to move at the time of their escape but soon after she started her nest she probably couldnt anymore and was cooccooned into place by her drones, like a queen would be when egglaying.
Thats my 5 cent.
