How many tests should you take?

Af was due today. No regular period symptoms. Woke up really nauseous the other day (only once) had a few very mild cramps the last few days, lower back pain which isn’t normal for my period. Took a test this morning and it was a clear positive.

But how many tests should I take? I’ve seen so many women on here talk about chemical pregnancies how do I test to see if this is one?