My parents are too much sometimes

I am very grateful for them and how much they care about me and my son, but they are so smothering sometimes. I know it's not intended but I feel like they doubt my parenting skills and my judgement and it's horrible. Again, I know it's only from a place of love but still, I feel like they second guess me a lot of the time and I can't help but be upset. I can't really approach them about it because I know they'd get defensive and offended and then sad, because I know they don't mean to make me feel like this, and most of the time I'm good at just letting it go over my head, but sometimes I can't.

Today my mother texted me to see how the baby was, so I said he's fine, a little grumpy today but he's good. I had two messages back saying to call her and why is he grumpy what's up, then 3 missed calls, a call from my dad, then a text from my dad saying to call him asap, is the baby ok, what's up with him? I texted him back when I could and asked what's going on and he replied asking if the baby is ok, so I said yes he's fine. He texted back saying to keep him updated on how he is or "if he gets worse" and then an hour later another text from my mum asking how the baby is now. HE WAS FINE! Poor kid was a little grumpy today, he's human!

Three weeks ago my mum suggested getting the nappy pants for him, and I said I didn't really like them and theres no need for him right now as he's not going to be potty training for a little while. He went to stay at their house for the night. When I picked him up the next day and unpacked his bag, all of the nappies I'd put in were gone (I always over-pack) and there was a few of the pull-up pants in there instead. I left them there ready for when he went back so she could use them if she wanted and the next time he stayed there she texted me saying I should be using them because they're better and easier, and when I said I just didn't like them for him right now she said to keep trying them and get used to it.

If I tell my son not to do something when my parents are around my dad usually says something like "oh let him he's ok", and it's like well no he's not ok because I've said not to do that for a reason, not just to be a dick. If I'm visiting them and mention that we'll be having dinner when we get home (with my fiancé) they'll insist on giving him something to eat right then because it's too long to wait, even though its not the time he usually eats at.

I know it sounds petty but stuff like this builds up and up and just really gets me down. I feel undermined all of the time. Just needed to vent :(