I took a peak at your foals. They have great stats for sure. I think you just have a lot of competition. I would keep showing the foals so that they level up and can be bred faster; to make up for the financial loss I would put a lot of horses to work in the Career Center. You can sometimes find some high level horses for sale or in the rescue that have high skill stats, they are good investments for making you money. 
The only other thing I think you can do if you want to perform well in 4 and 5 star is keep training your horses. Higher skills the better your horses will do. The good news is ever halter show your horse participates in they will gain skills and working in the career center will also gain them skills. 

For example, I have about 50 horses working on this account (my other account is my show account) and I have sent them to work twice and I have already broken even for the day for my daily expenses and the additional things that I have spent some cash on like Vet and such. 
Now you may not need 50 horses cause it is a lot to care for but with the right group of career horses you can easily show your best horses and keep making profits for your ranch. 

As Ryle said, the Halters are just full up to be honest. Even myself, I've off and on, been struggling with some showing in Halters AND Disciplines.

I've got a few Elvish Warhorses at 4/5* like you and I prefer to use Halters to level them up faster. Turns out, so is everyone else too, as adults or foals. I even turned the one adult, at that time, to make them run in Disciplines, Universal Tier at that, they were still struggling. So, I went back to Halters, because Halters do give out the best exp.

You can try Haltering them, until they are 2 years old and once at that age, you can try switching them to Disciplines and see if they do better there, but gaining levels would be a little bit slower, and on top of that, there is no guarantee that you wouldn't have full up options like I've ran into as well.

 Careering horses on the side, is also a nice way to go, plus even Exploring. Careers, is automatically, free money and at least some form of income. You can play games to earn income. Exploring in mines might net you some bits/ingots and gems to sell. Exploring in Hoofbeat Plains can net you wild horses ((if lucky and the such)). Treat items to sell ((like oats, apples, alfalfa etc)) or whistles ((lassos aren't in demand that much)) or even dyes, seasonal or not to turn around and try to sell too.

Ok thank you everyone I feel a lot better now, :)