Anyone on here gotten pregnant with an iud still in place?

I've tracked my periods for a long time but never anything else since hubby and I aren't trying yet but for some reason this month I just felt like I was preggo... And maybe since I thought that I'm just more aware of what's happening with my body but I have an avg cycle of 28 days and one <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">period tracker</a> I have estimated O on 3/14. On 3/17-3/18 I had really bad cramping and a lot of CM and even some brownish pink tinged CM. I assume that was when I actually O. Now 3/25 I'm having cramping. Is this all normal cycle stuff or should I take a HPT?