Well it sounds like the 54 was too big for you right now. As long as you don't have the seat height at max on the 52 I would just go with that. But you might want to check what it feels like climbing a steep hill out of the saddle. If it's too small you will feel cramped up and may even bang your knees on the bars in this situation. But you won't notice this riding on a flat road. As you gain more riding experience you are likely to raise the saddle a little and maybe want to be a little more stretched out, so you do need some room to adjust for this. You can easily fit a longer stem to stretch out more, so it's really about making sure you have some leeway on the saddle height.