Cramps, etc. May be pregnant?

Okay. I know a million people have asked the 'could I be pregnant question' but read on:

My husband and I had unprotected sex on the 14th of April. My period (according to my tracker application) was due on the 30th, and is now 4 days late. However, my periods are almost never normal (last period before came on April 2nd, and for 2 months before that it had been around the 15th).

I plan on taking a home pregnancy test on the 7th (making my period a week late if it doesn't come before that), I'm just really curious now.

I've been experiencing back pain (lower occasionally, mostly mid), and some cramping sparsely that feel like my period cramps (just milder). No nausea as of yet, and my breasts are no more tender than during my period.

Just looking for some advice to ease my mind for a couple of days. I WANT to be pregnant for those wandering. I've never been pregnant before, and don't want to freak myself out.

Any advice would be great c: