Aggressive Chiweenie

So I’ve had my Chiweenie since November 2017 and she’ll be 3 in June. She’s always been protective of my mom and I but since I had my son it’s 10x worse.

Before he was born, she would growl at anyone who came near me or my mom if she was sitting on one of our laps.

Now that my son is mobile, she gets snippy with him if he tries to crawl/walk to me or my mom (he’s a year old). We’ve been consistent with telling her no and putting her in her cage if she gets aggressive near anyone but especially my baby.

She’s only aggressive when it comes to me or my mom. If my son tries to play with her, by giving her one of her toys, she’ll gladly play with him as long as he’s not near me.

She’s getting worse as he’s getting around easier and I’m at a loss of what to do. I was thinking about a trainer but can’t find anyone around us (we live in the country in a really small town). I really don’t want to rehome her, obviously, but my son comes first. Plus I’m worried since I’m 27 weeks pregnant with my second. And she was bad before I got pregnant too so I don’t think that’s causing it.

Sorry if I’m rambling. Has anyone else experienced this and been able to solve it? Or have any advice??

TIA 😔