Is this relationship a good start?

hey, me and this girl were close for 3 months, i asked her out 3 days ago and i new she would say yes, because she'd basically asked me to ask her. problem is, after 3 days, im still not that happy even though i love this girl, its as if i expect her to do something heartbreaking or something, we know each other a lot so its more like 3 months we've bn together. all im asking is what can i do to make our relationship strong and is it normal for me to have doubts that she's gona do something big to ruin it, i cant help it but thats my instints