Am I eligible for U.S citizenship?

It all depends on the timing of the infractions. You told us nothing about it.

If you have been convicted of aggravated assault, and if it is a felony conviction, it is possible that you are not only ineligible to become a naturalized U.S. citizen but that if you file an N-400 Application for Naturalization it may lead to your being placed into removal (deportations) proceedings. You are highly advised to schedule a consultation with an immigration lawyer who practices in the area of immigration consequences of criminal convictions in order to discuss this matter in greater detail. You should bring with you to your consultation a court-certified copy of the court's records of convictions for your two DUI convictions and your aggravated assault conviction.

You will find the guidance that you are seeking once you visit a qualified and experienced immigration attorney who can properly assess and analyze all of the prior convictions and the ramifications on your eligibilty for naturalization. This forum is not the appropriate place for a personal and specific analysis of your case. Good luck to you.

My fellow attorneys here are correct, I write to emphasize that any noncitizen who has criminal history should, without fail, consult an immigration attorney before filing ANY application with USCIS, and before traveling internationally. Criminal activity creates a risk of deportation, or in the case of a traveler, being unable to re-enter the United States. Check first, and avoid regrets later.