If my transvaginal ultrasound on june 11said i was 6 weeks 3 days and the docs say i conceived may 11 is it possible i got pregnant from sex on apr 29?

Yes: Transvaginal ultrasounds are accurate but are not definitive to the day. Also if your ovulation cycles are off, that changes the date of conception.

Not likely: Those dates do suggest that you ovulated around 5/11. Semen from 4/29 could not have been still present. If there was fetal heart activity, i don't see how the sex on 4/29 could have caused the pregnancy. If the pregnancy is not alive then it would be possible since the pregnancy would have stopped growing.