Thank you for bringing your question to Just Answer!
Since she's told you that she wants to take things slow, I would keep contact to about 2 times a week...you want her to have a chance to miss you and to look forward to your calls.
That thing about being "too nice"...just be yourself, and don't try to change yourself to try to make her happy. Women like men who can make decisions, who don't always say "I don't know...what do you want to do?" and expect her to come up with all the ideas. She will appreciate that you took the time to think of something interesting to do and made the arrangements.
If you've gone on two "sit down" dates--meeting for coffee/drinks/dinner--it may be good to come up with an idea for a more active date this time. Is there a museum, exhibition, art show or some other place that you can take her? Anything that would have the two of you actively interacting. If you are worried about picking the "right thing," come up with two options and ask her which she would prefer. Presenting options is much better than asking her what she wants to do. Women like it when a man takes the lead.