Help please 😊😊

FirstName
So <a href="https://play.google.com/store/apps/details?id=com.glow.android.nurture">nurture</a> says I'm 4 weeks but I took a clear blue this morning that says I'm maybe 5 weeks along. Anyone know why they might be different? Or any tips on how i can find out exactly how far along I am? Any help is appreciated! I'm a first time momma 😘😘