Thick discharge help!

Anyone else on here get thick boogerish discharge throughout their cycle? I'm in the pill and my discharge is quite thick. Iv been on the pill for two years and have noticed it for a while now. The colour of it look yellowish on toilet paper but if I look at it on my finger it's white.

The last 5 1/2 months I have been worried that I could have been pregnant (due to strange discharge) but if had periods and negative tests so I don't think that's the reason.

I have also had a ultrasound and a MRI and they couldn't see anything wrong in my pelvic area.

What could be causing this discharge? I have also been tested for all STDs.

Any advise would be great!