I’m confused! Some help please!

I’m normally pretty regular, but last month (June) my cycle was off and my period was acting really weird and lasted longer than my normal 7 days and I had calculated my July period wrong. So I took a pregnancy test on the 15th (which came back as a negative) because I thought I had missed my period but really it was supposed to start on the 22nd. Fast forward to today and I still haven’t gotten it. On the 20th I had very light spotting once but it stopped as fast as it came. Well now I am having cramps and back pain but only on the right side. I had an IUD two years ago and gotten it removed this past March. I know it takes a few months for your AF to get back on track but I went back to normal almost immediately. I was thinking about taking another pregnancy test but I didn’t know if I should wait a little longer since I’m only 2 days late. If someone has had this happen and knows what’s going on with me, I’d really appreciate it.