Extended cycle BC to one month BC

I have been on an extended cycle birth control pill for well over a year. My periods on this pill were heavy and approximately 5 days in length. I recently switched to a one month birth control pill (28 day). My first period on this new BC pill lasted for only 3 days. The first day was normal, but the second and third days were really light and seemed more like spotting than a period to me. Is it typical to have a lighter first period once switching from extended cycle to a 28 day birth control pill? I took a hpt on the fifth day after starting my period. It was negative, but I didn't really look to see if a faint line was there because I assumed it would be a dark line. If it was faint, would I have noticed it? I have continued to take my birth control since and am expecting my second period on this pill in 17 days.