HCG Levels (So nervous)

So Last week I had a few obvious positive hpt's. Last Thursday (about 4 days before missed period my HCG was 8.11) I know a lot of people say it's Not positive until it's 25+ however where I work anything over 5 is positive. Had another one ran the next day and it almost doubled in less than 24 hours! First one was done Thursday at 9:15- it was 8.11. That Friday it was done about 8 or 9 and it was 15.62! So the fact that it almost doubled in 24 hours when they say it should double in 48 made me happy! However, it worried me because I see so many saying on here they have levels of 900-4000. It's been 6 days since I had it tested last and tonight I'm having it ran again to find out my current levels. Anyone else have levels on the lower side and still turn out to have a healthy pregnancy? I will say I continued pregnancy testing and the line continued to get darker each day since last week so that's a good sign that tonight's levels should be much higher. I am now 4weeks 3 days, so please keep me in your thoughts 😔. I'm praying for a sticky bean! This is my first pregnancy so I'm over analyzing and worried about everything. It also doesn't help that almost every post mentions miscarriage in a lot of the comments on here 😞 I never realized just how common it really is..

I'll post the photos of the hpt's below and then update you guys once I get tonight's result. I'm