Why won't any Tokyo Mew Mew groups accept my art!?

Maybe it's an idea to make your own group - I don't think there exist a group especially made for Tokyo Mew Mew fan-manga/comics (though I'm not 100% sure). I think it would be quite nice if there was a group like that.

Also, I took a quick glance at your comic. Possible improvements might be to first make a draft on what you want to show on the page and then make a neat version (where you first draw the comic boxes where you want them with a ruler(nice straight lines look better) and then add the characters, text balloons and background). 
Also,  take your time when writing text in the neat version, your handwriting isn't horrible so if you slow down with writing (maybe write while keeping a ruler horizontal - I'm not sure if what I'm saying is really clear, but I hope you get what I mean ><). If you think the text isn't neatly written, erase the parts you don't like and write again - time consuming but the result would turn out really nice.

I only took a quick glance, but I think improving on layout/neat boxes and neater text would greatly increase the audience since it would make the comic easier to read.
(also I noticed that you have a lot of comic boxes on one page, if you have the feeling that you have too little space in the neat version, don't rule out the option of taking another piece of paper - you might even be able to add more detail in larger boxes (that is, if you like))