I don't think she looks strong in your flatwork pics, but hard to tell from a still. I assume she is as you have her in a gag. Cracking pop on her though!
No, I can't say she looks especially strong But the position of your foot, in wellies, in the third pic/jumping looks a touch risky. Please be careful.
I don't think anyone could tell from a picture, but she must be VERY strong to ride at the bottom of a gag ? ? How old is she, i would be careful not to ruin her mouth if she is young.
And also i have to second the wellies i have seen two terrible accidents with people just riding in wellies and certainly wouldnt jump in them.
In response to the original question ;does she look strong?
Honestly no she looks from those couple of pics like a sweet little horse that is working steadily and quietly.
She is however being pulled in by the bottom ring of the gag with a rider on top that is tipped forward and using the gag as leverage to make her appear to work in an outline. Its very hard to say anything else based on those pics.
By the look of your foot/leg in the 3rd pic i dont know how difficult it must have been for the pony to recover from the fence when your foot was pushed so far through the stirrup compromising your leg position.
Hope you dont mind the honest opinion but on the plus side she does look like she has a lovely jump.
How does the pony go in a snaffle?