Hello
Thanks for your query.
I will deal with your query in two parts.

Question 1 - Why would you have had a miscarriage ?

There could be the following reasons for this :
1. Most common cause of pregnancy loss is genetic causes. There could be a chromosomally ( genetically ) abnormal fetus which did not develop normally and miscarried. For this, ideally the aborted tissue should have been sent for a genetic analysis. If that was missed, you and your partner should go for a karyotype.
2. Intrauterine infections - Get yourself checked for STDs, Rubella, toxoplasmosis, cytomegalovirus etc.
3. Abnormalities of size and shape of uterus can lead to miscarriage.
4. Autoimmune disorders - get laboratory evaluation for antiphospholipid antibody syndrome.
5. Hormonal imbalance - this could be the common link between your scanty periods and the miscarriage. When hormonal levels are deranged, you fail to have normal periods, and normal ovulation. Thus the egg formed is defective and can lead to abortion. Also, when hormonal levels are inadequate, the growing embryo fails to receive proper support, leading to abortion.
6. Routine tests like complete blood count, blood group , liver and renal function tests etc - rare blood group incompatibility etc can be a cause.

At 34, the egg formation is suboptimal, and the abnormalities in egg formation increase, so maternal age is a contributory factor incriminated in abortions.
For future conceptions, please consult a Genetic counsellor / high risk pregnancy expert first, who would give you a comprehensive check up and testing and then treat you accordingly before going for planning a pregnancy.

Question 2 - Why would you have a scanty menstrual flow ?

1. Anxiety, stress, weight gain or loss rapidly, hectic travelling, job or personal traumas, ingestion of hormonal medications or other medications that affect the menstrual cycle, recent illness, fever etc = all these can reduce the menstrual flow.
2. Polycystic ovarian disease - here the hormonal imbalance leads to formation of multiple follicles in the ovary, but none mature. So the woman experiences delayed and scanty periods, and defective ovulation. Get yourself tested with the following investigations - FSH, LH, PROLACTIN, TSH, FASTING SERUM INSULIN, GLUCOSE TOLERANCE TEST, SHBG, ADRENAL HORMONES etc. in addition to a pelvic transvaginal ultrasound.
3. Decreased ovarian reserve - This is the opposite end of the spectrum , where due to rapid ageing, the ovary loses its capacity to produce eggs, and those which are produced, are also suboptimal. AMH, FSH and antral follicular count are the tests to diagnose this.
4. Endometrial disease
5. Thyroid hormone dysfunction.

SO, your menstrual irregularities and the miscarriage COULD be related, because the causes overlap and ultimately have a bearing on your health , well being and reproductive ability.

Please consult a gynecologist / High risk pregnancy expert for thorough investigations and evaluation before embarking on your next pregnancy.
Have a healthy and active lifestyle, take regular folic acid supplements, maintain an ideal BMI and stay positive.
All the best for your future pregnancy.

Take care, and feel free to discuss further.

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There is no reason why you should not be able to conceive succcessfully.
YOu are most probably having scanty periods, as in normal flow, your pad or tampon would be soaked by itself, instead of the flow being evident only when you use the washroom.
Yes, the miscarriage could be an isolated event also, but at 34 years, you would do well to have a thorough evaluation and then plan a pregnancy, to increase your odds of a successful conception.
If you have been screened for the 3 conditions mentioned, get yourself worked up for the rest of the list, just to be on the safer side.
Please stay positive, as the main culprit for both menstrual irregularities and pregnancy losses is stress, which negatively impacts the hormonal axis.

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