I can't cum I just pee!

I won't judge, but I do think you need to think about what you are doing and why, as well as the consequences. You only lose your virginity once, and it cannot be reclaimed. You have asked for help, but really you need to give more information if you want proper help. So I need to ask some questions!

You raise a number of things that need to be sorted before you have sex, and I really think that a week is not enough time. It is not a mechanical process that works exactly the same way for everyone.

I suggest you sign in to talk about the things you raise so you are adequately prepared. You haven't given much information to be able to set the scene. There are some things that cause concern for your 'whole-being' welfare - that's not to be judgemental, but to give real help.

Are you sure it is pee and not ejaculation?
Why are you 'supposed to' have sex?
Why is it with your ex-boyfriend?
Why next week?

Then questions about the detail of what you have said which leave gaps in my understanding.

What happens (apart from the 'pee') as you build up? At what point do you 'pee'. How do you feel afterwards?
What do you mean by'instead of cumming I pee'? and then 'I can't orgasam either'? What technique do you use?
You talk about sex, but you haven't mentioned contraception or protection against STIs. What have you decided about that?
You are 'pretty young'. So what age are you?
What do you mean by 'really developed'?

There appears to be something dark in the background that worries me, and I want to help. So please answer the questions, and I will try to help as well as I can.

Take care