Can trans-vaginal (internal) scan harm baby when listening to heartbeat?

[RainbowHope4]

I'm posting because I'm so worried.
I'm pregnant for the 4th time (I've had 3 previous MC's).
I'm 7 weeks pregnant. We went for our first scan at our IVF clinic the other day.
I had an internal scan and she put the sound on and we heard the heartbeat.
She put it on for a long time (well about 30 seconds).
I panicked when she did this because I thought it was too dangerous to do this before 12 weeks due to there being too many sound waves being passed through to the baby which is too much for their little heart.
This is what I've read previously. And at our last clinic they told us they wouldn't let us listen to the babies heart because it was too dangerous at that stage, and it should only be done at 12 weeks onwards.
So now I'm panicking that harm could have been done.

@RainbowHope4

Medical professionals' often simplify things eg the picture you get of your baby is taken using ultrasound that is created by a transducer changing the electricity to a sound wave that is beamed into your abdomen, the sound is then returned to the transducer that converts the sound into a digital format that is displayed as an image on the screen with the option of printing a facsimile of the image on paper.

But most people will say it's a picture of your baby.

A transvaginal scan goes into your vagina. it doesn't enter the uterus at all. so no where near baby so can't hurt them. i had several in the early stages of pregnancy as got a much clearer image that way and i'm 31 weeks now.