Welcome

so the official advice is that anything that happens between ovulation and AF is the same whether you're pregnant or not and that symptoms don't typically develop until after a missed period. However, so many women have symptoms that are unusual for them and then find out they're pregnant so you know your body best. I think there is an element of being more aware of your cycle once you're TTC and noticing things you may have disregarded before, but I totally believe early symptoms are possible because so many women have experienced them.
The best time to take a test is first thing in the morning as first wee of the day is the most concentrated. I think the HCG levels double around every other day when pregnant so of course you're most likely to get a BFP if you wait longer - but who can wait?! Early tests like the First Response ones can be taken up to 6 days before a missed period, so 5 days before your period is due. However if you test 5 days in advance and get a BFN it doesn't mean you're not pregnant.
All in all, you're not out until AF shows so it's worth trying again tomorrow morning if you don't want to wait for AF to be late to test again.
Good luck