Legs and ankles swelling

18 weeks with baby #6. I have never really experienced swelling in pregnancy this early. But is it normal for one leg/ankle to swell and not the other? I am currently on a very high dosage of blood thinners and I have been since about 11 weeks. So I do not think it would be caused by a clot because I do not think any new ones would form. The ones I have and have been treating are in my lungs not in my legs. Anyone else experience swelling on one side?