Jake,
First off, never change too much from before you got together in order to remain congruent in your actions / personality.
With that aside here are two points I'd recommend sticking to if you're afraid of being too nice:
1)
Always be "one step behind" in the relationship. What that means is being a little less invested than she is. And every time the relationship escalates to a new level, she has to be the one initiating it. Whether that means becoming "official," spending more time together, meeting friends and family, moving in together etc. it all has to be appear like it was 100% her idea. The trick here though is to be only one step behind. If she is thinking about moving in together, while you're still hesitant to meet her family, then you're really not on the same page, and she will most likely become insecure.
2)
Never invest more into the relationship then she has...ever. In an ideal world, a relationship would be 50/50 give and take. Unfortunately (or fortunately depending on how you look at it), You'll want it to be closer to 70/30, even 80/20. And investment can be a number of things such as:
-she drives to your place (especially if it's a long drive)
-she cooks for you
-she initiates phone calls or text convos
-she pays for dinner, lunch etc.
-she does things for you..errands, cleaning, fixing things, anything really.
Basically, it just means anything that involves her putting time, money, or emotion into you. So what you want to do is take all that into account and give back roughly 1/3 or 1/4 of what she puts in. This seems absolutely harsh and may even generate a little controversy, but it is sadly true.
Both of these points just relate back to investment. You may already have this article, but if you haven't, it's excellent on the topic of investing:
https://www.girlschase.com/content/its-n ... s-hers-you
That's how to avoid "white knighting" in a relationship.
-Doc