The only indicator I see that you might not be ready is that, you guys are having sex in her parents house, and worried you will get caught.
Adults do not do that.
1 they can get a room or an apartment.
2 if caught it is no big deal, because they are mature people who are deemed responsible by their parents.
If you fit into either one of the categories, then you should not be having anxiety like you are. But if you do not fall into the above, then that is while little jumping johnny decides to shrivel up at the slightes noice.
Lastly, how can any of that be pleasurable? You are scared you are going to get caught. How can that be fun at all. You need to take your time, relax, play and enjoy. You need to be a real lover. Not do it like rabbits or dogs, and have it over with.
Im starting to ramble.
I do not mean to be harsh to you, just adding my observation. I do not know you, and could be totally wrong. If so, my minor apologies. But, if there is the slightest chance I am correct, or what I am saying applies to you, then give it some thought ok???