Keep getting positive digitals and positive FRER, the test line just doesn’t get darker than light pink. Read please💕

So I’m 11dpo (will be 12dpo in like 30 minutes lol) and got my first positive at 9dpo. I’ve gotten all positives since 9dpo even though they’re not as dark as the control line but very visible and pink! I got three positive digitals, two this afternoon and one tonight. I know I should stop testing but I’m just curious as to why my test line on FRER isn’t as dark as all the BFP’S I see on here? I’ve read that the digitals require more HCG and I’m getting positives on those so shouldn’t my lines be getting darker on FRER (they aren’t faint they just are light pink). This may sound silly I’m just curious? Is this normal?