That rack is so epic, I cannot even imagine what her bra size is.
She probably can’t find one that remotely fits (especially in the US) but I’d guess she’s at least an M cup in UK sizing. An I cup doesn’t exist in the UK, the equivalent is a G cup, so if she’s still stuffing herself into bras that size it means she’s wearing ones approximately 10 sizes too small.
Or to put it another way, loading 17lbs of tits into a bra designed to only carry 4lbs.