Hi, I'm an RN and I can tell you that heparin and levonox are basically the exact same thing. They are often used interchangeably in hospitals. The major difference in the molecular weight. Otherwise they do the exact same thing. However, you shouldn't be taking heparin and aspirin 325 at the same time, it might thin out your blood to a dangerous degree. You usually have to do an INR to monitor the blood clotting ability and to ensure that your blood isn't too thin. In many cities there are community health centers that can do the needed test at a low cost.
I have a blood clotting disorder and have been taking lovenox my whole pregnancy. My doctor said I'll be on it 6 weeks after birth and then there is no longer extra risk so you should be all right at this point.