It is exactly my situation. Very soon I have to close one door and I have to open another one. Of course there are some external aspects as well, but it is rather an inner problem. Probably once you are familiar with such changes it is not an issue anymore, however there are some things to whom you should say goodbye. Friends, colleagues, places, work, habits, etc. I almost forgot: the plants. I kind of like them and I hope they like me too, I mean the plants.
There is always a feeling of emptiness. Of course this will be filled with those new things once you open the new door but this in-between situation is kind of awkward.
Letting go is probably the hardest thing to do.