First of all, you two have some very wonderful aspects together---so do not blow this Neptune stuff out of proportion.
Venus sextile Venus, Moon trine Sun, Moon trine Pluto, Saturn trine Mercury--All of these help to build a nice supportive network of understanding and solid communication.
Now, as to the Neptune issues---I think you spelled it out for yourself by saying these words:
"...daughter is my world and she’s all I have. I want so badly to be a good mother.."
You seem to be putting a lot of pressure on yourself and her, by making her your 'entire world', and saying 'she is all you have.' That puts a very intense focus upon her, and perhaps you should try and expand your life a little, to alleviate some of that intensely narrow focus.
For her to feel a healthy relationship with you, she might not want to feel that she is your entire world and she is all you have. That is a lot of internal pressure.
I think she would rather see you having close friendships, maybe some romantic ones, or not---but a somewhat larger world than just her.
As you say, you never felt you had the love and attention and nurturing that you should have had. So obviously you really want to give that to your child. That is a positive thing. But be careful not to over do it.
Neptune square Moon. And Neptune square Venus/Mars.
The Neptune squares can be positive, in that they can make you both very sensitive and attuned to each other and you both want to have an emotional connection.
But my concern is that you could both misread or misinterpret each other.
Your Neptune squares her Cancer moon. At times, you may not see clearly what it is she needs. You may mistake your own sensitivity, baggage, old wounds, for her own needs/feelings/desires.
She may need independence, as she matures, when you respond with enabling or 'dependent' building reactions, because of your own troubled childhood.
So it will be of vital importance, that you learn to communicate clearly with each other, about what is needed for her best interests/growth.
For example, her Cancer Moon will endow her with great emotional strength, but also a certain amount of emotional turbulence.
Especially as adolescence approaches, she will have some tantrums etc.
Your neptune square will be impacting her emotions. You MIGHT take her tantrums too personally and give in too easily. She may need boundaries, wherein you would be too yielding?