Formula Switching

I have low milk supply so I wasn't able to breast feed my son how I'd originally planned. He also has a milk protein. allergy. After being on Similac Sensitive, to Similac Soy Isomil, the pediatrician switched him to Nutramigen for the allergy. The powder form does not have DHA & ARA, but the ready to feed does & he does not like the ready to feed. Is there anything else any mom's can recommend cause I feel like he's missing out on this nutrients & I just want him to be healthy