Please post your desired output from your example.
Better yet is to show 2-3 examples and the desired output for each of them.

As far as I can tell there is only one string that is between a G(...)and 10+ more G's. Your question is not clear. Your code is not right. Given the string: "GGCTTTCCGTTGTTGCTGGGTGTGGGGGGCGGGCGAGATTGGAAGAGCACACGTCTGAACTCCAGTCACGCCAATATCTCGTATGCCGTCTTCTGCTTGAAAAAAGGGGTGGGGGGGAGGGGGGGCGGGGGGGGGGGGGGGAGGGGGGGAG", please explain in english what you want to accomplish.