No she was not only waiting for you to finish but she actually mabe enjoying it until you finish that way she knows sex is over. You see most women do not need to cum everytime to signal end of sex,  that is why most are not bothered by men who cum early. in most cases the man is the one bothered. Most women the pleasure is actually emotional than physical, same as what happens when you enjoy making her cum and squirt all over, sometimes you do not need to also cum in order for you to say that session was great. 

But your issue  is a very common fear that most men have about lasting long and what enjoyable sex is like for her.

First of all you need to know what 'long' really means. A man who reaches his orgasm in 4 minutes while his partner is done in 3 is long enough. But, a man who takes 15 minutes while his partner takes 20 is not still long enough. So, the first thing you should know is what your partner thinks about it. Don't assume that a certain time is considered long and don't think that lasting 45 minutes as they show in porn is necessary.

Secondly, if you really don't last that long, know that intercourse is not the only way to please a woman. Several researches argue that it is almost impossible for more than 60% of the women to reach an orgasm through penetration. So, it hardly matters if you last 30 minutes too. Learn about your partner's body. Learn what she actually needs. Most of the women enjoy oral stimulation of the clitoris rather than penetration.  

Third, if you feel you are not long enough for her, use foreplay. Women love foreplay more than men. And, sometimes they find it very simulating. So, your best way would be to indulge in more foreplay than usual, [take your partner to a high, and then penetrate her](https://exoticsex.home.blog/2020/04/30/female-orgasm-101/).

Good luck ….Enjoy!!!