period/or implantation bleeding on birth control?

I have been on birth control for six years, I have an alarm on my phone that goes off that I take my pill at the same time every night! My most recent period started the exact day and time it always has along with cramps, but later that night the cramps went away. The period was definitely there but was no where near as heavy as it usually is, but it lasted about 6 days like usual. The nurse at the doctors office told me as long as it comes in between that week of pills it's fine. The switched my dosage of pills about 3 months ago, I don't know if this would have an effect. I just want to know if this is normal or if it's something to worry about. My breasts have become tender a little sooner than they usually do before my period, and I have had episodes of frequent urination...?