If you think that your son is suffering from ADD or ADHD then take him to a counsellor. They will evaluate him and let you know. He has to undergo several tests conducted by the school therapists to determine whether or not he qualifies having a 1/1 aide. What you say at the IEP meeting does not count as much as his performance in the tests as the latter would determine whether they assign an aide or not. It is very very hard to prove whether a student needs a para. Generally, the only way a student gets a para (that is paid for by the district) is to have a severe physical disability. You can find out whether your school has an inclusion class where there are two teachers. There should be a special education teacher and a general education teacher. These classes are usually smaller, which will not only help limiting distractions, but will also offer your child a higher opportunity to be refocused more often with the assistance of the second teacher.

Let your son grow normally. Keep reading to him and asking him questions about what is happening around him and ask him why they happened. Use complete sentences when talking to him. This will help build his vocabulary and reasoning skills. Above all,
relax.

Working with children with severe disabilities needs a qualified instructor and you seem to be one. To start with you can have a discussion with people involved in the same field so that you can get an idea about the new job. This job requires a lot of patience, attention, and perseverance. You have to deal with issues of safety when lifting and moving children. Your employer should be training and supporting you in this.