thoughts?

kirsten • Married for 4 years. Currently have a one year old princess💜 and a 1 week old prince💙
I've been testing to see if my BFP's are getting darker. The first response and clearblue test lines are getting darker but when I test with an internet cheapie (wondfo), they are the same and i've had one that was lighter. What are your thoughts on this? could I be having a miscarriage or should I just not trust the wondfo tests?