Yes! My son started two hours of speech and two hours of O.T. a week for several years starting when he was 2 1/2. I always say that I feel like I am playing the tv show Survivor with him. I have to outplay, outwit, and outlast him.
One of the methods that worked well with my son was for me to pick one area of improvement and to make a graph. The visual helped him identify what behavior I was looking for. For instance, when I needed to potty train him, he would not go no.2 in the potty; no matter how many stickers or candies I offered. Finally in frustration (I needed him potty trained to go to preschool; which he desperately needed) I made a chart. I drew 10 brown clouds. I even called them poo poo clouds. At the end of these clouds I drew an equal sign and then I cut a toy from a magazine I knew he wanted. Every time he pooped in the toilet (wasn't consistent at the beginning) HE got to color the poo poo cloud in. He completely two to three graphs before I could finally say he was fully potty trained.
As you know, he is aggressive because he is frustrated. As his speech improves, this should lessen. Also remember that routine is important because he can predict what will happen next. I bought a pocket chart calendar (can be purchased at a teacher's store) and I made people dress in different clothes for what we would do. A kid with a book = going to the library / A kid with a backpack= going to preschool, etc.....
My son still will not wear t shirts with words or pictures of characters and forget about drinking out of restaurant kid cups (they have pictures too). He still occasionally has a hard time defining his space and will bump into people. But overall, he has come a long way. Especially when I think I wondered if he would ever talk and now he is a second grader in the top 1/3 of his class academically and talking all the time.
So, keep your head up high, celebrate every little victory you get with him (they do add up) and remember to take deep breathes.
You can private message me if you need anymore ideas. I find the more 'out of the box' they are; the better they work.