Excuse my grammar, the story may be long-winded, but I try to make it as short as possible.

Hey everyone :-)

So i’ve met this girl around 3 years ago at a party (Its the best friend of the girlfriend of my best mate). I flirted with her, she flirted back we had a great time and ended up in a hotel having great sex. After that night i wanted to get to know her better, so about a week without any texting i texted her to ask her out.

In which she rejected because she wasnt looking for anything at that moment. I accepted it and moved on.

But this is 3 years ago.I've seen her multiple times after that night (with friends) and i always spot her staring at me.About a week ago I was with friends again and she was there too. After a nice evening and some drinks i brought her home. I was too nervous to ask her out at the time. So I did that a few days later via text (asked her out for drinks). She said she didn't have time at that moment, but still wanted to play tennis with me (we talked about that that night). So we scheduled the day we would tennis (which was yesterday).

We had a good time, and after we were done tennising i asked if she would like to go back to my place. In which she declined, but said she would like to ''next time''.But i didnt want to make her feel like i'm to pushy so i did not ask when the next time should be (or maybe i shouldnt of asked her that at all)

I'm very bad at picking up signs/signals and i'm usually a closed person, but i really would like to know her better.

What did the ''next time'' mean? Should i ask her out again, or let her take the initiative?

I think you should make her feel like you really want to know her, so I guess ask questions, let her speak : listen to her! You should actually tell her, you want to know about her. If you can communicate this, she might feel comfortable with sharing things about herself. She will feel secure and safe with you. Then sex will come naturally.

Next time means : I didn't say no but I didn't say yes. It's a big maybe which can become a future yes. It maybe means, you will need to work on it, before we spend the night together/ maybe she doesn't want to have sex with you but said that because she doesn't want to be the girl who says no to a guy/maybe she didn't want that night in particular/
Did she flirt with you or any sign of her body showing you she wants more?

You seem to want to know her, then ask her out multiple time and see how it goes. Because she might feel you only want sex with her and not the emotionnal part, if it's not the case : show you care ! I don't think asking her about going in your house was a bad decision to be really fair, you communicate with her what you wanted. I don't think there is something wrong with this since you already slept with her (but that's my view, some other ladies would want the tension to be build and then it come naturally from the both sides), but I think it's a great thing you didn't ask her " when is next time" it would have been a turn off since you are pressuring her into something she might not be in the mood with.

Conclusion : you should tell her you want take time to know her, that's why you would like to spend more time with her and getting to know her.
Next time is a big maybe for me, that's why you might have a chance if you take the opportunity to ask her out and spend time with her. Women like when a guy show interests and initiatives about their relationships, that's why don't be afraid to ask her out.