Repeated first trimester abortions can be due to many reasons. Its necessary that you get your proper work up done for it. As you said you got your D&C done, i would like to know what was the report like. If it showed corpus luteal defect , it can be a cause of abortion.
Since you conceived twice spontaneously, so you dont have any problem in conceiving. The problem is your pregnancy
There are many reasons for first trimester abortions; most common chromosomal defects, genital infections, uterine malformations, metabolic causes etc for which there are appropriate tests which your doctor would do.
You need to get yourself evaluated forr the problem of not conceiving only when its almost one year and you have not conceived.
I also advise you to start FOLIC ACID
tablets if you are trying to conceive as it would avoid many causes of abortions.
Still if you would like to get yourself worked up for not conceiving, you should meet up a doctor who would advise you step wise tests of infertility
and husband seminogram.