Jen, APS is diagnosed by tests, not symptoms. One or more of the following tests must be positive two times; further, the 2nd round of tests must be conducted at least 12 weeks or more after the 1st round.
or beta-2 glycoprotein 1.
** Don't be alarmed by the phrase "lupus anticoagulant". It's a weird misnomer and actually relates to APS, not to lupus per se. BTW, there's a "sticky post" (permanent info post) on APS that you should find helpful. The "stickies" are located right above the user threads.
The events that most often raise suspicion of APS are miscarriage, stillbirth, strokes and TIA's, *obstructive* blood clots, and pre-eclampsia. Meaning, your "uterine clots" may or may not be germane, but only a doctor could say.
Also, because you said that your anti-ds-DNA was in the range deemed negative, not positive, that's another reason to worry less.
BUT if you're still worried, if you have a family history of autoimmunity, ETC, you could discuss your APS concern with your OB. (I'm thinking "OB" first, because that's the dr. most familiar with your pregnancy & your C-section.)
Of course it makes sense to be familiar with APS and lupus, their symptoms, diagnostic criteria, etc. All women should be! But please don't convince yourself prematurely that you have lupus or APS, as self-diagnosis can sap people of energy better applied to the better things in life!
It's a fine line, I know, between legitimate and illegitmate worry. But you don't want your doctors to to stop listening to you or taking you seriously: you need them on your side. After you talk to one (or more) of your doctors, let us know if you want to discuss their responses. We're always here. Sending best wishes to you & to your new baby, Vee
P.S. Taking aspirin daily may affect any new labs done. So if new tests are recommended, in your shoes I'd inquire about taking aspirin BEFORE the tests, so as to get "truer" lab results.