Disappointment with Hearing Test

My son has Audiotory Neuropathy Spectrum Disorder along with mild deafness in his right ear and more pronounced deafness in his left ear. He has been wearing hearing aids since he was six months old. We thought he was getting better, because we weren't able to discern much difference in his hearing when he wore them. When he was 6 months old, he would wake us up in the morning with his babbling.  He's been in speech therapy for about 6 months and showing improvment. He's making more sounds that actually seem like words. Today he told his speech therapist, Shannon, "Buh bye" and waved his hand as she left the room. We were all amazed. He talks so much more than his sister, who doesn't have a hearing impairment, so it's a bit disappointing to have a hearing test like he had this morning.
Funny, I thought he was getting better because he seemed to hear the same with or without his hearing aids in his ears. I didn't think that the reason his hearing was the same with or without aids was because he need more amplification. Why didn't I think of that? His last ABR (acoustical brain stem response) was markedly improved over his first one back in April. I thought his hearing was improving, but after I saw his test results I wonder how much he is not hearing.  He can hear speech sounds in his right ear but his left ear, that's a different story. So it looks like he is going to need another sedated ABR and more behavioral response hearing tests to determine what is going on in his noggin.
His audiologist at Callier Center for Communications said the next step is to turn up the amplification in his hearing aids and if that doesn't work we should consider a Cochlear Implant for his left ear.
Disappointing...
On the bright side, we caught his hearing impairment early. He is getting speech therapy and we provide a language rich environment for him at home. He has good  receptive and expressive  language skills. We are fortunate to live in Dallas with a very good medical school and the Callier Center. I'm also thankful my husband and I didn't take the advice of the first ENT we saw for him. We trusted our gut instincts and got help for Nathaniel sooner instead of waiting 6 months before we had him retested. By the time Nathaniel was 6 months old he had a MRI ruling out a audiotory nerve dysfunction, an ABR, and his first pair of hearing aids.  He's now 14 months old, we'll have to see what the next 6 months hold for him.