Who just knew that they were pregnant before they tested- is mother intuition to be trusted or can we invent symptoms that don't exsist?

We weren't going to try this month, we decided to wait until after our holiday in Melb in a few weeks. However, we DTD on O day and even though we used a condom we didnt use one for the 'whole show'.

Now I just feel like I know I am pg, I have had nausea for the last 3 days, had a couple of spews, sore veiny boobs. I am busy telling myself that I am just making it up, how could I possibly be experiencing this symptoms so early on- but there is a little part of my brain that is telling me that I am already pg.

So is there anyone out there who experienced pg symptoms very early on, and just felt like they 'knew' long before they were able to test?