DHEA in women partially converts to estrogen as it is a precursor to estrogen. If you are concerned that your estrogen levels are too low then by all means ask your doctor to run a full endocrine panel on you. Since DHEA can raise estrogen levels, it seems as though your doctor may have felt that would be enough to adjust them, but without a specific baseline for your estrogens, it's impossible to know precisely.
Your doctor should make the determination as to whether you need supplemental estrogen, but I would insist on the bio-identical form as it is much safer.
Another issue you need to be aware of is xenoestrogens or "endocrine disruptors." These are environmental estrogens that could be blocking your natural estrogen at the receptor site. Check out my page on "environmental estrogen," and take steps to eliminate these from your body as best you can.
This will allow the natural estrogen that your body produces to work more effectively because it does not have to compete for receptor sites with the endocrine disruptors I mentioned above. This will also lower your risk of breast cancer because it is the endocrine disruptors that actually cause the problems in breast tissue.
So once again, DHEA in women does raise estrogen levels, but you also need to have a full workup done on your hormones and try and get the environmental estrogen out of your system.