My mum is forgetting he is my son!?

I have a 7 month old boy who I love. He is my mums first grandchild, she has had all girls and when she found out I was having a boy she was over the moon. She was great at first helping me out and giving me loads of support, but now it seems like she is forgetting he is my child and not hers. She has took him away on holiday for 3 nights and when she came to pick him up I was still giving him breakfast, she took the spoon off me and took over, I was crying because I was going to miss him so much and she had a go at me for it. She is very interfering in my relationship with my husband and every time she comes into my house (she just walks in and never knocks) she goes on about how dirty it is, which it isn't, I clean every day and make sure it isn't dirty. There may be some toys or shoes on the floor when my husband comes in from work or I have been playing with my son but that's it. She has even said to me she will call social services if I don't 'buck my ideas up,' when I asked her what she meant she wouldn't tell me.... and I still to this day don't know what she means by it. She wants me to go back to work early and my husband give up his job to take care of the baby, I don't know why but I think she may try an manipulate him in some way and I know this may sound crazy but I'm convinced she will try and take my son away from us. It started off as a niggle in the back of my mind as I was constantly reminding her he is my son so it is my choice, this was all over getting him christened, I don't have the money to do it and am not willing to skint myself for something I don't really beleave in anyway. But now it is always on my mind when ever she calls and come round and it is really worrying me that she may try and use my PND to take him away. He is so well looked after and never goes with out I love him so much and am really scared she will try this. What should I do?