Ttc question

So I spotted 4 days after I should have conceived and then i continued to lightly spot on and off for about 4-5 ish days after that. ( I would have been about 4 ish weeks ) since then no signs of an actual period or blood ( I am 19 days late in my period ). Should I test? No symptoms though that I can really think of besides some lower back cramps every now and again and I threw up about 2 weeks ago which could have maybe been a bug.