MalorieP,
You are going to have to ask your surgeon, mainly because, he is the only one that actually knows what structures you have and how they are working. This is not like a regular "vanilla" total hip replacement.
After a fusion, you may be lacking certain structures that a needed to control stability of the joint. Some of your muscles are going to have atrophied to almost nothing, because they have just not been used in the last eight years. And, only your surgeon is going to know this.
At the age of 20, you should be able to see the surgeon by yourself, if you do not want to discuss this very important aspect of post-op activities in front of your family. If you are married, your partner should actually be part of the discussion. It is very important for your partner to know what type of stresses NOT to apply to your hip.
This is a very common question asked of total joint surgeons. Your surgeon probably is not as "uptight" as you think he is. Address to problem just like you would ask any other question about your post-op limitations.
If you do not want to ask the surgeon yourself (which you really should do), you might ask his nurse about it first in private and ask if she (or he) can help broach the topic.
AAHKS (American Association of Hip and Knee Surgeons) has quite a bit of information on sex after total hip replacement. If you Google "AAHKS, sex after total hip replacement" and go to the AAHKS link. Scroll down to the bottom of that link and there is a whole bunch of links to information on sex after THR. Some even have illustrations.
However, again, you are not going to have a regular total hip done. You really, really need to discuss this with your surgeon. If you can't talk to your surgeon, write him a letter and give it to his nurse. That is one way to break the tension.
Good luck on your upcoming surgery.