How come you are not dual yet? If you were sworn.. then you are a US citizen. Aren't you a citizen of the Philippines already?
Also:
> So that means I can use my Philippine passport to fly to the Philippines from the US
Technically (ie legally) you have to depart with a US passport, if you are a citizen (does not matter if you are a citizen of 10 other countries, too).
In practice, they do not check. So you show the TSA officer/airline your Philippino passport + they let you board (there is a small chance USCIS is conducting extra checks - I read it happens in Miami periodically. In that case... all bets are off - they may not let you board the plane. But you have to be REALLY unlucky. Also, if they catch you, they cannot punish you - there is no penalty for violating this law. At most you do not board the plane).
> BUT I have to make sure I have my US passport when I fly back to the US.
The airline will likely not let you board the plane (when flying back) without a US passport. However, if you can somehow make it to the border (either at an airport - by persuading the airline to let you fly, or land border - Canada/Mexico - or some port, if you come by boat), AND can persuade the immigration officer you are indeed a US citizen (eg via a copy/picture/... of the naturalization certificate/social security number... basically whatever evidence you have), you cannot be denied entry. The hard part is making it to the border.
You can also apply for an emergency passport w/ the US Embassy in Manila (this is typically issued in 1-2 days. It is of limited duration - basically just to get you back). Or you can apply, in Manila, for a real passport + hope to get it fast (I got mine, from another US embassy, in 9 days).