Question: Hi, I have a question with regard to the accuracy of dating gestational age from LMP with irregular periods, and whether a pregnancy might be viable with the following details:

I have had irregular periods for the last 6 months or so, possibly due to weight gain or per menopause. My LMP was on 7/12, and I had a watery/bloody discharge for about 4 days starting 8/4 which I originally thought was an early period. I am 43 years old and obese.

I was having very unusual symptoms - heart palpitations, dizziness upon standing, and pain issues, as well as a feeling of anxiety - and went to the ER on 8/16 thinking I was having a heart attack. While there, the doctors took a pregnancy test and it turned out to be positive. That week, I took two additional HPTs because I wasn't entirely convinced, both were positive.

On 8/23 I woke up with a very watery brownish discharge, and we went back to the doctor. The transvaginal ultrasound detected a low sac, but no other detail. My HCG was 577. They estimated the pregnancy at 5 weeks or less, though from LMP it should have been closer to 6 weeks.

8/26 I took another HCG test and ultrasound. My HCG had not increased much - it was 590 - and the ultrasound showed a single gestational sac containing yolk, but no fetal pole. The mean gestational sac measured at 0.67 cm, indicating gestational age of less than 5 weeks. No fetal heart rate or placenta was visible.
The vaginal discharge has continued, though it varies between thick, tarry brown (usually overnight) and watery brown or maroon. There have been spots of more blood-like color and consistency, but it's mostly been dark brown tar or watery maroon brown.

My OB has indicated that she believes the pregnancy is not at all viable, and has suggested three options (wait for natural miscarriage, methotrexate, d&c). I have had a previous miscarriage which was physically and emotionally agonizing, so I am extremely anxious about going through another. On the other hand, I am not reasonably sure that with the confluence of symptoms that I don't have a very early pregnancy, as my OB did not mention the irregular cycle issue. (I saw a ARNP in her practice for the cycle issues). So I just want to know, given the information, how reasonable is the EDD of mid-April? Is it possible I ovulated later and have a later EDD? Is the determination of non-viability reasonably good, based on ultrasound and HCG, or would following up with further exams and/or labs provide a more accurate idea?

Thank you.