Ema, Hi!
Just because you here illegally doesn’t necessary mean you need a lawyer.
It’s your choice.
I file for first I-485 after being illegally in US for more then 4 years also.
I filed myself.
If you can read and write English, understand the instruction and feel comfortable to organize, file and keep truck of your applications and other documents, then do it yourself.
But, if you don’t feel comfortable, or familiar with the law, then you better hire a lawyer to do it for you.
Lawyers deal with cases like this every day and if you can afford one, then you might be better with a lawyer. You will spare yourself of some extra worries, by paying him or her to file and follow up on your case so you can concentrate on something more pleasant in your life.
Good luck to you and good choices!
