can someone please give insight? test lighter

Tori
**Update** 
I read a lot and took another test with 2MU and another by adding water to it to dilute it. They were BOTH darker than my FMU test. 
I hope I can help anyone in my situation.. I spend 30 mins crying this morning when it was lighter. I need to start thinking more positively.
I've been taking tests every few days since I found out and they have been getting darker.. my test today at 5 weeks 6 days was lighter than 3 days ago.. has anyone had this happen?