Irregular cycles, starting Clomid and afraid

I have had very irregular cycles since my periods started. They are usually long though, at least 45+ days. They are also usually heavy.

I had an hsg this month and I got my period after just a 21 day cycle. I don't think my cycles have ever been so short! This period was much lighter than normal.

I am on cycle day 4 and still bleeding. I am set to start my first round of Clomid tomorrow at cd5. I am terrified that something is up because of my weird period. I have taken two home pregnancy tests and they were negative. I will take one again tomorrow before I take the Clomid.

Everything I have read about implantation bleeding says that it wouldn't last 4 days and wouldn't be heavy enough to fill pads/tampons. It is light for me, but it is not spotting.

If we finally are pregnant, I certainly wouldn't want to do something to harm the baby! But more than likely it is nothing, I have convinced myself that it was our month more than once.

I have also read so much about Clomid that I am scaring myself. I am sure that most people on here have used Clomid and had healthy babies. I would love to hear those stories!