TTC for 1 year. Unexpected bleeding. Help?

[Younginlove]

Hi, my name is Vanessa. I'm about to be 21 in october. I haven't had a proper period in probably 2 years. My husband and I had unpeotected sex on september 10th and yesterday (september 20th) I have light bleeding when I used the restroom. And a couple of days before that I had light spotting when using the restroom.

Also, I have hypothyroidism and am on medicine for it.

Any idea what this bleeding could be?