This is a bit of a frame challenge. You asked about official flying races, but is it possible that you just want to fly, and that the race need not be official, or that the feature could come from another source?
Two things hinted at in your question led me to propose these two solutions, in addition to the existing excellent answer.
1) Work with the DM on a homebrew race
You mention getting a winged kobold by replacing pack tactics with flight. Negotiating with the DM to realize your vision makes perfect sense. You may be able to take the stats of an existing flying race and reskin it to match your concept, or, as you suggest, trade a racial feature for flight.
2) Get flight through another method
Is it possible you just want to fly, and it doesn't have to be a racial characteristic?
As we're getting to higher levels I think a flying race may no longer be as much of an issue
That suggests to me that the party as a whole is increasing in level, and new characters come in at or approximately at the level of existing characters. Often when that is the case, DMs grant one or more magic items to a new character to put them on par with the existing party.
If that is the case, you might be able to negotiate with the DM to give your new non-flying character a magic item that grants flying. Two popular ones are:
There are many others. If you want to pursue this, you might be able to talk to your DM to work something out.