Scottymctotty wrote:Why am I so afraid to have sex, and please how can I overcome this? I'm afraid that if I don't do something soon I might end up losing her and because I'm very shy it is hard for me to get a girlfriend in the first place.
There's one thing right there, you're putting enormous psychological pressure on yourself. Then she's tried to initiate sex too and that's more pressure.
Are you genuinely sexually interested in her? I apologise if that sounds like a silly question, but if you're thinking "it's her or virginity for ever" you might be trying to override your own tastes and preferences, which wouldn't choose her in normal circumstances.
Is the environment she's suggesting for sex a quiet, undisturbed, safe one? If you've got worries about housemates or family walking in on you, that's going to be yet more pressure right there.
What do you think she'd say if you said you were very inexperienced and wanted to take things slowly? That doesn't expose the anxiety side of things that you said might put her off, but could mean she's more gentle with you and willing to explore and play a bit rather than rushing into full penetrative sex.
3 weeks doesn't seem very long to me either. People do it after 3 minutes in some cases, but if you're interested in a relationship and not just a quickie, then I agree with IceBlock that it might just take more time than this to build trust.