xDestro, I'm impressed that you are weighing your options and not just jumping into an already made decision; that shows maturity.
#1- electrician is a good trade with many, many levels of pay and options available to someone willing to put in the work. Taking a pay cut now at 20 to put your apprenticeship in is a smart thing. You've already proven you can budget and save money. You and your girl will find a way to make ends meet.
#2- vehicles. Ugh.
I don't know what kind of truck you have, but, consider hanging onto it as a work truck. If you buy another vehicle to use for outside of work stuff, you don't need to blow your load on it. Carrying a balance on a credit card will build credit, too, and you will (hopefully) have more control over how much it costs you. Your 5k finance might cost you 8.5k in the end!
Also, depending on your state, you may be required to have full insurance coverage on your newer vehicle if you have a loan on it. Even if it is a beater.
You may also qualify for a multi car discount through insurance if you keep your truck.
Good luck, young man. I have a feeling you're going to be just fine!
Josh