It is natural to feel sick to your stomach contemplating the possibility that you don’t hear what you are hoping to hear upon bringing up a “what are we” conversation. However, try not to let that keep you from doing what needs to be done.
You are right, after 4 months of consistent dating, it is time to have the “what are we” talk. To bring it up, simply start a conversation letting him know about how much fun you have had with him so far. This will set the right tone for what is coming next.
He will most likely agree with you and will also tell you how much he has enjoyed dating you for the last 4 months. Now that you have put him in this mindset, it is a lot easier to segue the conversation into what the both of you are. Just ask if you are his girlfriend.
That is really it.
No need to make it anymore complicated than that. It is better to know now, no matter how the possibility of getting a response you don’t want makes you feel sick to your stomach.
Better find out now than invest yet another 4 months or so into this relationship only to come out empty-handed in the end.