OK, after investigating further, it looks like you must carry HbD and a beta+, as you do have a small amount of HbA. If you carried only the HbD, your HbA level would be much higher.
The significance of this is that if you pass on HbD and your partner passes on beta thal, the child would probably be similar to you. However, if you pass on the beta thal trait and the partner also passes on the beta trait, the child could inherit both and be thal intermedia to major, depending on how severe the deletions involved are. If both are beta+, intermedia would be more likely.
CVS is the earliest detection method. The only method to ensure the child is thal-free would be PGD and IVF.