Dear Lucy,  

I suspect you don't have a spiritual director, and I think you need one. Things seem to be so changeable that you need to look for more stability in your life. I would not advise someone to "keep on thinking" indefinitely, or even to change a mature decision they had already made, unless there are substantial reasons to do so. You will need someone's help in order to examine and see if your reasons for changing, putting off entrance into religious life and becoming interested in another congregation are substantial.  

If you have a pattern of frequent change in your life you will find, if you join religious life, that your reaction to the normal difficulties will be the desire to give up or make a change. So before you join a congregation you have to have your mind made up not to jump into something else the moment there are difficulties and something else catches your eye. 

God bless.