I.G.
First let me say that I am sorry for what you have been through!
If your miscarriage was within the first trimester and a single occurrence (no history of miscarriage, gynecological disease, STD's and no apparent cause) it was likely just a genetic "fluke" in which the embryo didn't develop properly to support the pregnancy and should have no influence on your ability to conceive.
Now whether or not you should be worried after TTC for 6 months depends on a variety of factors. One is your age and the other one how "seriously" you have tried, meaning how frequently do you have sex and are you aware of your ovulation patterns.
If you are over 35, you have been charting and are able to correctly interpret your basal temperature and have sex frequently around ovulation you might want to consider speaking to your doctor. Simply because you are of "advanced age" and if you need help conceiving you might want to get started on diagnosis and treatmeant without trying in vain for years while your fertility declines even more.
Now, if you are under 35, or if you have been trying more casually, or you don't know your ovulation patterns, then get a good book (I recommend "Take Charge Of Your Fertility), learn how to interpret your body's signs and TTC in a more "organized way".
If you have not conceived after a year of regular, unprotected intercourse you can consult your Ob/GYN and go from there.
If you are in your 20ies you may even wait longer than that if you have the patience.
The chance to achieve pregnancy is only about 20% per month, even with perfectly timed intercourse. Normal conception rates are: 70% in the first 6 months, 85% by 1 year and 95% by two years without infertility treatment.
Good luck!