Early pregnancy

I have question about the first few weeks of pregnancy I hope someone may be able to make sense of. Ok so basically I’m 4 weeks pregnant on Saturday. Now I have already gotten numerous BFPs since Wednesday which can only be possible after implantation (right?) but yet every pregnancy app says you don’t implant until your in week 4? So I’m confused, I need reassurance that I have implanted and if I have does that mean I’m like 5 weeks? Probably too obsessed but after a missed miscarriage last time I need to know everything 🙈

TIA Ladies ❤️