Technically speaking, failure to comply with any condition of your deferred adjudication order can be grounds to adjudicate you guilty and sentence you. It sounds as if you have done very well on your community supervision except for being behind on your community service hours. That being said, the probation officer could contact the prosecutor's office and they could file a motion to adjudicate you guilty. Whether or not that is likely to happen really depends on the probation officer and your relationship with him/her.
If they were to file the motion to adjudicate, the result could be many different things. They could adjudicate you guilty and sentence you anywhere within the punishment range for the offense. They could extend your deferred adjudication. They could modify it in some way, ie give you more hours to complete, or they may not do anything at all. It is difficult to say but at this point, all you can do is to finish your hours as soon as possible and hope for the best. Do everything on your deferred adjudication as perfectly as possible and make sure that you do not give them any other reason to adjudicate you guilty.
Hope this was helpful and should they file a motion to adjudicate, I certainly recommend you contact a lawyer to help defend you. Should you want a more detailed answer, you may contact one now. It may help you worry less and sleep more easily. Good luck and I hope you finish your deferred adjudication with out any issues and can put this behind you.
Mr. Zientek's answer was very thorough and correct. Just get your hours done ASAP and, given that they have not done anything about your being late to this point, it is not likely they will do anything to revoke your probation.
As far as trying to get an early termination, AFTER you finish your community service hours, you might ask your probation officer what they think. You were not in compliance with the timing on the community service but you did complete everything.