There's a lot of contact on the curb rein in these photos. And it doesn't look like you're using very much leg. And your hands are very low. I am guilty of all these too. I have a horse who is inclined to ball up and rush everywhere. To lift the front end and slow the rushing takes a lot of leg, hands carried as a pair up and forwards and giving and holding with the seat. Or just ride on a loose rein and relax. Maybe if you could share some photos where you haven't got so much of a contact on the curb we might be able to see what the problem is more clearly, because, to me, from these photos it looks like the curb is pulling his nose in.