Need help

Donna
I had my impant out on the 7th of October that week I was on my period since I came off I haven't seen a period since my <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">period app</a> says I am 19 days late I always come on time I have done pregnant test but nothing I am getting cramps and backaches what do u think