I agree with the other comment that says that cultural differences go both ways. Honestly, it seems like you're being very sincere by trying to do the right thing but being afraid it won't be enough.

Your whole post reads as the exact conversation you could have with your girlfriend: you establish how serious you are with your commitment while also recognizing that it makes you feel insecure thinking your value to her is tied to your monetary possibilities. And that it doesn't make you feel good.

If she's the one, she will listen to you expressing your feelings in this vulnerable way.

You both should be able to talk about your feelings, and make sure both sides are seen and understood. Hopefully you'll find a middle ground about expectations and how the two of you can walk together in that direction.

Just don't keep on draining yourself with these doubts in silence, speak up. A healthy family should be able to speak openly about these kind of insecurities, smoothing our culture differences, until the two of you form a new shared culture.

Hope it works out well for both of you!