My point of view

Sorry to say this but you do favour the younger too much, the oler one feels that and it is hard for her. I have two girls aged 6 and 1, when my younger one was just borned, the older was so jealous because she used to have my attention 24 hours a day. One day she told me : Mommy smiles at meimei all the time but not to me. From that day I told my hu*****and and myself to show our love to her in words whenever possible, lots of hugs and smile to make her feel that we love her just as much as meimei.

My suggestion to you: Hold your older one in your arms and tell her you are sorry that you were a little bit overprecting meimei because she is younger but that does not mean you donèt love her, you love them exactly the same. Sincerely apologize to her and from now treat them equally. 

Once the older feels you are fair she will start love meimei as much as you do, there is nothing else make me happier to see my two girls play and hug and laugh together like the most silliest persons on earth and I know that when the days both me and my hu*****and are gone they got each other and we can rest in peace. Good luck!