Sounds to me like it is working out for them... I feel like while it may take time (and it always does), all to soon they will be the best of buddies and you will wonder why you worried so much about it!!

Took mine about 4 months when I got Samantha, but that was over WHO was here FIRST!! I had Giz and Amy for almost a YEAR when my neighbor FINALLY let me have Samantha so Giz and Amy thought they had been her first and she didn't belong here.. (Fur flew some, believe me!!) Samantha had been here for a year and moved away and that is WHY I got Amy.. So Sam thought SHE was here first and they didn't belong here.. SOooooo, we had fur fly often, over who was here FIRST!! Now, they play and tolerate each other.. NO sleeping together yet, but they will play!

(Samantha was my neighbors cat that lived on my doorstep 24/7 crying to get in my house. I would let her in and she would stay 3, 4, 5 days before the neighbor would come get her. After she had kittens in March this year, she kept one of the kittens and finally gave me the Mama that I had been begging her for, for 2 years!!)