My first pregnancy was unplanned but at what would have been at around 4 dpo I felt so dizzy at work. At 8 dpo I had an upset stomach. I tested at 10 dpo and nothing. So I left it but the day before my period was due I had a really vivid dream thay my husband was carrying a baby on his front in a rucksack but I couldn't see the baby's face but could hear it saying 'I'm here, look!' I woke up in a sweat. Next day I tested and got a positive!
I had very similar symptoms at around the same time in my next, planned pregnancy.