Throughout this thread everyone has been assuming you have Echinodorus bleherae, the "common" sword plant, and you probably do, but it might be another species, there are several very similar-looking "species." I put species in quotes because some botanists believe these close species are actually one and the same, though as Dr. Kasselmann points out in her book, the growth habits are not always similar which would tend to support different species.
Regardless of that, in my experience E. bleherae initially grows relatively slowly. I have three large plants in my 115g [jschristian44, you can see them in the photos of the 115g Amazon riverscape tank under "Aquariums" below my name on the left] which have twice produced several inflorescences each this past year, with dozens of adventitious (daughter) plants. Some of these I separated after a few weeks and planted them in my 10g and 20g, and after several months they are not to the surface yet. I find this species tends to grow to the tank somewhat. As yours are largish now, trimming off the outer (always only the outer which are the older) leaves may result in a slightly smaller plant.
In your initial post, you asked about "a little brown" on the leaves. This is not a problem, the existing leaves may well die off within a few to several weeks; provided you see new growth from the centre of the crown the plant is fine. But are you fertilizing the tank? Echinodorus plants are very heavy feeders, and they will not do well without added fertilization. Liquid such as Flourish Comprehensive or Nutra-fin's Plant-Gro will suffice. Substrate fertilization is good with swords, but given you do not want them over-growing your tank, I would only use liquid.