As other have said, well done for reaching out. It's a brave things to step back and question ones self. It also shows how important it is to you that you are willing to change you to have a relationship with your grandchild. Such a positive starting place.
Also as others have said, it is very early days for you all, taking your time and being understanding is the best way forward.
Remember , remind yourself, that she is a new mum with new mum challenges, hormones, sleep patterns, body changes, life routine changes to name a few.
She, like any new mum, has a lot to adjust to.
While I do understand you wanting a relationship with your grandchild a month old baby won't know if you see them every week or every month. Sad but true.
Building a good pattern of visiting with and relating to the bay's mum is what is going to get you to a time when your grandchild does understand and knows you.
If you want to have a life long relationship with your grandchild the foundations start now and they won't be strong if you put her under pressure.
She is a New Mum with new mum stuff going on, remember.
She is finding her feet. She will pull away from you if she feels under too much pressure or if she feels her and her family are being attacked or criticised.
I'm guessing she is looking to her family for support as you've said why baby's dad isn't there to form the family group.
There are 168 hours in a week so for 166.5 hours other people are her support.
Make you 1.5 hours with her and baby count as a positive experience for her and you.
She is the key to any future relationship you have with your grandchild and sadly YOU have to PROVE to her and her family that you are a SAFE person to be in THIER lives.
Because it is in Their lives. Your grandchild doesn't exist in isolation of Mum and her family.
Other people get 166.5 hours - sleep time - to influence her mood, choices, behaviour etc for good or ill.
You have to make yours 1.5 hours be good for her and wanting to "Take HER Baby Away From Her" isn't going to work in your favour as much as I understand why you want that special time.
As hard as it is, please, don't get yourself into a place where you Demand YOUR Time because you've negotiated that time with her for you to have access with your grandchild.
You had to "negotiate" to get your time, with her baby, that was a win for you right there.
The situation is fragile and you've done a great job of realising how fragile your situation is so you can improve things for everyone.
My mum used to say "Kill them with Kindness" and so often in my 70 years she has been proved right.
Bitterness and Battles only bring pain and destruction. You don't need that in your life, non of us do. Lets hope you can find a way forward to a joyful time with your grand baby.
May Kindness to yourself, Kindness to baby's Mum, Kindness to your grandchild and Kindness to other involved in their lives bring you some peace and a life long loving relationship with your grandchild.