Hello and welcome from New York. I have had the same problem with my Rowenta traveling iron. I just bought my 4th one. I have yet to find a travel iron that is this size and steams beautifully. All the others have leaked exactly the same. You would think that the company would invest in finding a solution to this.
On this note I do have to say that when I add water to a cold iron it spills out the sides more than when I heat the iron first and add water, never to the fill line, just below it.