As she does things to show you that she is trying to change then you should do one thing to show her that you are more comfortable with her. Being a professional she is probably use to telling people what to do and being in charge and it's hard to keep your professional life separate from you personal life. Try to have open communications and compromises but no matter how you try to work things out in your relationship it will never work if you don't have trust in it or in your partner, letting your guard down can unconditionally open your heart to many possibilities in a relationship, it can move mountains in your relationship and allows you to explore a long term relationship, it never makes you think twice, it can make you do things you never thought possible.
You can't say you will take care of her and always be there for her but after a few months you totally neglect her and makes her the least of your priority. In building a relationship, you have to put in the effort if you see her putting in an effort also. Don't say it for the sake of saying it. You have to learn to make your actions match your words. You can't say you will be loyal and truthful to her but after few months she sees you dating other women. In romantic involvement, having a credible integrity is significant because your partner's only way of trusting you is through your words, unlike in work where they have references and just base you on that but in relationship, when you say it's the past and you're a different person now, your partner will hang on to that irregardless of your past. So always keep in mind her feelings along with yours so that the way you have acted in the past does not come back to bite you.
Each time she shows you that she has changed then you do something to show her that you can be more trusting in her like if she doesn't complain about you hanging with your friends then you do something to show her that you are letting down your guard like let her know something about you that you would have never told her before. It's going to time and actions for this relationship to get back on track but honesty is always the best policy and she will respect you more if you are honest than if you were to lied to her and cover up your feelings all of the time.
That is what relationships are all about taking chances and believing that the person loves and cares about you enough to not hurt or reject you. Maybe if you told her about the things that you worry about. You don't have to do all of it at once but a little at a time will make for an easier transition for you both.