Usually, you can get receipt within 3 weeks.
If not, you need know whether USCIS receive your application or not. Without receipt number, you cannot do anything. No one will answer your question if you call USCIS.
So only thing you can do is pushing your lawyer. Call your lawyer and let he tell you what happens. Check cashed? or mail delievery conformation?
6 month is crazy. Maybe you need file another 140 if no any information you can get.