Your acupuncturist is really the person to ask as they are more deeply familiar with your medical history and your signs and symptoms from a Chinese and Western perspective.
To answer generally, however, yes the IUD, particularly if it was copper, is known to cause heavy bleeding. The clotty blood is not “causing” your miscarriages, but the damage to the internal tissue may be contributing, or you have other issues that are far deeper than that (these are the ones your acupuncturist should have better clues about).
And, yes, acupuncture is very well applied to the entire range of menstrual issues and fertility issues. That said, if you are have frequent miscarriages - it’s not uncommon to have rougher cycles, heavier, possibly more clots, more cramping for 1-3 cycles following each miscarriage. But, again, your acupuncturist should be able to discuss this with you more deeply as they will be in a much better position to ascertain whether your menstrual issues seem like they arise from a deeper more historical set of factors, more from the IUD, or more from the miscarriages - and, obviously, all are involved.