If you used the same bull, the problem is not with the bull. Fall calving heifers are coming off of poor late summer grass and have lighter calves. You think you're doing your winter calving heifers a favor by feeding them, but all you're doing is making the calf bigger. We used to have some of those 125 # plus calves and the same problems. We stopped feeding the heifers anything but good quality hay the last trimester and now have very, very few problems. High performance cattle grow fast! In the womb as well as out. Regardless of what the "experts" tell you about nutritional requirements the last trimester, stop supplementing your heifers and you'll cure a lot of your problems.
