Can I be denied entry to US while ACD is open?

I am an F1 student and I had a case of unlawful possession of marijuana (less than 30gs 221.05). It was a big one time mistake. I was ordered a drug evaluation which I passed. My concern is immigration. There is no guilty plea involved in my case and my lawyer informed me that I won’t have trouble at immigration. I plan to make travel abroad in the next two months before I graduate in May. I can’t avoid this travel as once I graduate it will be difficult to travel. But my ACD period remains open during this time. If I am denied entry then my graduation will be affected. I plan to carry a certificate of disposition of my case and also the drug evaluation report. I wanted to get a second opinion on what I should be expecting at immigration. Can I be deemed inadmissible or deported for such a thing or is there something I should be worried about?