I would have to see your pics. There are a number of reasons that this could be happening. I have a feeling that you may just not lean ehough yet, but of course, I can't say for sure. Even with fluid retention, your abs will show through if you are very lean. Abs are one of the last areas to get lean. Take a pic of your back and compare it to your front side. Usually back conditioning is behind the conditioning of your front area. This may give you a better ideal of how lean you really are.
Here's another thought. Part of the issue my be that your abs are not developed enough. The thicker they are, the more they will show through. If your abs are shallow, you may have to be low single digits to get your abs to show. So work your abs more, using high reps to burn them out, every other day. You can only grow so much new muscle at once but it may make a difference over time and if your abs are shallow, it will certainly help in the long run.
3rd, you may need more AI. Fluid related to test is often retained in the mid section. Drying out with more AI might help to tighten your stomach up.