Not to ring my mum if she doesn't ring me?

[whathappening]

I can see this is going to sound petty but hear me out.
I live quite far from my family and usually visit every 3 or 4 months.
Up until recently either I would call my mum or she'd call me at least once a week.
I noticed we hadn't spoken for a couple of weeks so I rang and we chatted and everything was fine, this happened a few weeks in a row so I left it and thought I'd wait for her to call me as it's always me ringing lately, anyway she didn't so I called her again and now it's been well over a week and she's not called.
Do I just keep calling her to maintain contact or do I leave it knowing she may never ring me again?
It feels very one sided and I had always thought we were very close.
When I do speak to her we get along really well and have a lovely chat, I just don't know why the calls have become less frequent and only if I ring her now.

It may not be that a mother cannot be bothered to get in touch, but may simply be trying to do the right thing, or, more likely, not do the wrong thing.

I'm not sure I buy this as a reason.

If you don't want to disturb or are worried about your child being busy, then you can text and ask if it's a good time, or to arrange a suitable time to call.

It shouldn't all be left to one person to get in touch all the time. It takes a matter of seconds to pick up the phone or send a message to show you care.

Perhaps she thinks you're busy with work etc and doesn't want to pester you?

If she's been a good Mum otherwise, I would let this go and continue to ring each week.

Yes, if it’s not because they don’t want to disturb you but because actually you are of absolutely no interest to them then yes it is.