Hi Danae
I've been there before and it's awkward I know.
I also find that some people are very thick-skinned and almost back you into a corner so that you have to be assertive - I'm sure they don't mean to - but equally I find it hard being assertive with other mums (despite the fact that I'm a confident woman)
I also know what you mean re having little enough time for the things you do enjoy - and for me that means the people I enjoy too...
All you can really do is consistently be "busy" and not instigate any chats. Maybe don't go to the toddler group for a couple of weeks so she's forced to latch on to somebody else?
Have re-read what I've written and I hope it doesn't sound too mean - I've just been there before myself (I'm my own worst enemy as I'm naturally a friendly, outgoing person - but I never expect to have people 'latch on' as they do)
You're right to put your own needs first. I do hope no one else thinks I'm a selfish cow!!!