That is a disappointment. Frankly, probation is the usual offer on a non-violent
first arrest, unless you had enough drugs to be your area's kingpin. The DAs see reducing your original charge to a D as a break. To me, however, a felony and probation is a felony and probation, and employers, etc., can distinguish between a misdemeanor
and a felony, but in the greater scheme of things they would be unlikely to know the difference between a D, C, or B probation offer on a drug case. So it's a break on paper only and not for any real life practical purposes.
Is it horrible? Well, no. But does it give you anything important. No, it doesn't do that either. If your lawyer's wheels are turning maybe she can pull a rabbit out of her hat yet, the least thing they can do is offer you a program and a chance to work the case off of your record. I imagine your lawyer is thinking along the same lines, so don't give up on it yet.