Mil is not a suitable babysitter. Someone else will be!
The way you're behaving communicates to your baby that it's only safe if you're there the whole time and you being there the whole time is a reasonable expectation for her to have.
At this age, many babies have separation anxiety and might cry if their mother is out of sight/away for a bit - with a sensitive and caring approach you can get them used to this and understanding that you going out of the room or house for a bit doesn't mean you're gone forever and they're still safe and can trust other people.
I don't think it matters hugely at 9mo, but as time goes into toddlerhood on you don't want your child to think other people = not safe as that's an unpleasant anxiety to have and won't help her learn and develop confidence.
I know a child who has been raised this way and he's (now 6) still upset when his mum is out of the way, only she can get him from school, she has to sleep in the same room as him etc. It's suffocating and not good for anyone's mental health.
Starting school or nursery when you've only ever been at home with mum can also be much harder.
Your baby is still small but I'd ask to get help with this and see if you can slowly become comfortable with someone else caring for her in small chunks.