Well it certainly sounds as tho she is getting plenty to eat.
Has it been confirmed she is pregnant by your vet ? Only reason I ask is that last year i thought my little one was pregnant and was confirmed in foal by my vet and so, was "feeding for two" It turned out she had lost it somewhere along the way and became unwell.
Not knowing this, I continued to feed, only i was adding to what she was about to endure. "Laminitis"
I would hate to see any horse go thru this, it was cruel to see her in so much pain and to have to keep her locked in a box for 2 months wasnt fun for her either.
i will say she has made a wonderful recovery (im even considering breeding her towards the end of nov early Dec)
She will never be able to have free run on pasture anymore, only small periods of time as a treat, as the sugar in the grass is just so high.
I really hope she is pregnant for you , so many wonderful people on here to help along the way and see how patty progresses.
Sorry for the long winded post just wanted you to be aware