@Roselvve,
If you have concerns such as this, you should be going to the cops.
Rape is a serious accusation and a serious charge.
But let's look at your symptoms/condition.
Clothes are on. Do you honestly expect someone who cares so little for you as to rape you in the night would have the decency and wherewithal to dress you back up exactly the way you were before? That they would have taken notes or photographs to get it absolutely right (e. g. correct hole on your belt if you were wearing one, panties correct side out and not worn backwards, bra on the correct hook, shirt tucked if it was, coat still on and zipped or buttoned just like it was before, etc.)?
Bloated toward the end of the month. And you normally get your period at the end of the month. Could it be ... your period?
Nervous and paranoid. Unfortunately, one of the most annoying facts about our female bodies is that, when we want our period and we are nervous and scared that we won't get it, our bodies decide to **** with us and delay our periods.
You said nothing about a guy's cum inside you or on your panties. 'Nuff said. Rapists are not so lovingly considerate - not even those that are trying to hide evidence - that they would clean up all traces of semen.
You said nothing about feeling sore. Not a 100% indicator but you usually have an inkling that something has happened. Don't believe me? Then try masturbating with penetration and little to no lubrication. Because rapists don't give a **** about lube or desire.
If it really, really bothers you, you can always buy a pregnancy test from the drug store,
follow its directions to the letter, and take it.
Chances are extraordinarily good that nothing happened.
However, if this is a concern of yours, you need to watch the drinking and hanging around people who drink. And pay attention to your own concerns about someone. If you feel someone was capable of this, why are they your "friend" in the first place?