period problems update

Charlotte•Louise
Well, I've still not come on my period. Was due 4 days ago. Glow is now saying I'll come on tomorrow. So we will see. 
I took a 3 for 99p pregnancy test yesterday all 3 saynagative. 
Is this normal not to come on when due? 
I've had the implant in since I was 13 had 1 changed over and had it taken out in September this year. So I have no idea if this is normal. 
Still considering taking a more expensive test but I'm tired and kind of sick of the nagatives. 🙈
What should I do?