I kind of agree with Ron...a 300/2.8 and a 1.4x TC would be VERY handy for swim meet shots. I used to have a 200/2 and a 300/2.8 and a 300/4, 70-200/2.8,100-300 f/4, an some other lenses, all at the same time, and was shooting one to four weekly sports assignments for two local-area newspapers. I found that on my then 1.5x crop Nikon D2x at 5 frames per second in full-field and 8.2 fps in 2.0x High Speed Crop mode, that firing rate was not as important as timing, and waiting to see the right shot, then shooting the shot at the precise time; however now that camera firing rates have gone way,way faster, perhaps 14 fps would allow you to get that one,single,good shot split into 3 or 4 frames on either side of the "ideal" shot. I found the 200/2 to be the fastest-focusing lens I have ever seen, and useful with the Nikon 1.4x TC 1.4e-II. 200mm x1.5x FOV made that basically a 300mm e-View.
For example, when a breast stroke swimmer comes up out of the water, and the water is draining off of the eye area and the nose, there's that little "curtain" of water...I think if you could have a camera that shot at 14 fps, you'd be able to trigger off 3- to 5-frame bursts of the best action, and have more to choose from. At five frames per second, there's typically only _ONE_ single frame that's clearly the best.
But...does 14 fps have autofocusing, or is the focus locked at the start of the burst? If so, it might not always be useful.
I dunno...you live in California, where the light is beautiful and bright...but still...I think the 100-400 at f/4.5 to f/5.6 is a bit slow, aperture-wise, BUT it's really a fantastic range for a full-frame camera! 100 to 400 millimeters is really a nice focal length range for outdoor sports like swimming.
I don't want this to sound condescending, but I think maybe some professional training, some lessons from an actual, qualified professional sports shooter, might be worth more than any new camera or lens. I bet that you could find somebody who could give you some high-level instruction,and that that might help your shots more than new gear. I looked at your Facebook pages a week ago,and saw some swim meet stuff: I think better shooting positioning and "working smarter" is mostly what you need to do. Just some basic tips, some strategies, and you're there.