Help me. Is this normal?

I dont know if this is normal.I have been on birth control for about four months now and my period used to be ridiculously heavy like I had to wear an extra heavy tampon and a large sleeping pad to hold my period in and as of lately the last 2 months I go through about 1 to 2 pads a day only.

It starts off where the blood is pretty much black then turns to dark brown then turns to dark red and it’s heavy with lots of large blood clots. but it’s not heavy not like what I’m used to and it’s kind of worrying me.

I don’t know what implantation bleeding

is and I haven’t had sex but I’ve been sexual with my partner.

A week after my period last month I took a pregnancy test which was negative. Also went to my dog day 3 of bleeding and she gave me a pregnancy test which was negative. (Needless to say I sound crazy since I’m not shaving sex)

This starting period started just like last months dark brown blood almost black 2 days before period and then dark brown thick blood and blood clots and now dark red.

I’m new to the pill and all of this help me someone please.