They are easy to mate. Mate them just like say a chinese. Place the male on a surface and let him calm down. Once he does take your female and place her several inches in front of him and make her walk away from him. If he is ready he should jump right on.
Sounds like your room is a bit cool actually. Give them more time. I would at least wait until they have been adults for at least a month. I found them very easy to mate.