7 weeks post partum, been having pregnancy symptoms, clear stringy EWCM lasting 2 weeks+, unprotected sex 16 days ago, negative pregnancy tests.

Negative tests. If your pregnancy symptoms were caused by pregnancy then this implies that the hormone levels are high. If true then the pregnancy test should be positive. If you are not wanting to be pregnant again then you will need to use condoms and/or start a form of birth control.