Hello there

and welcome to TTCAL,
It's very unlikely at 3dpo to experience symptoms since the egg wouldn't have even had a chance to implant yet... not until about 7-10dpo, even up to 12dpo does the egg start to implant and at that time you'd notice cramping maybe even some spotting. (IB or implantation bleeding)
It could be IPS (imaginary pregnancy symptoms) when our minds play tricks on us as much as we want to be pg OR.... that your dates are off and you're further along dpo than you think.
Good luck and hang in there, you will be able to start testing in about 6 days! That's not long now... @ 9dpo it's very low chance to detect hCG, but some ladies get their BFP on 9dpo (esp if you're father than you think)
So good luck
P.S.~ if you do announce pg, please remember to put (pg ment, preg ment, pregnancy mentioned) in title... thanks in advance