Bring the pink kissing back, its part of good fishkeeping to know when to bring a fish back.
Most LFS will let you trade for other fish... so just consider it an adjustment instead of feeling like your giving something up.
A bigger tank will not fix the problem unless its a supremely large tank, and even then you will be extremely limited in what fish you can have with those two kissing gouramis.
Hey, we all have done this at one point in our fishkeeping lives, buying too many or too large a fish to fit into our current tanks, hoping we can get a bigger tank in the near future. I call it 'Big Tank Syndrome'.
Fish do not 'stop' growing because of tank size... but poor space and water conditions will slow it down, but is that the kind of fishkeeper you want to be?
I think you want to be a good fishkeeper, otherwise you would not have asked the question.
Call the fish store, tell them you want to trade your fish in for something else and then bring them in.
Personally, I like Cory Catfish and perhaps some otto algea eaters to keep the tank cleaner.