If speaking in front of the group isn’t working right now, divide and conquer. Begin by speaking to smaller groups of 2-3, or individual conversations. Once the individuals in the group see you as a valued member, the group will follow. Also, maybe you should look at yourself when you are in a group and see if you are contributing. If you are quiet most of the time, then it’s easy for others to ignore you because they are uncomfortable with your quietness. Try to assess your situation and try to find a positive way to start talking and giving honest opinions.