It took time, but it does take time, it took for you to do the same things (picking holes in everything you do over and over again to become your norm) so you have to consciously do the opposite, every time you start to pick holes catch yourself and stop, you don't have to be positive about your self just be neutral. I actually thought of it in a way that do you know what I'm not that fucking special that anyone cares how I speak look act etc, everyone's far too worried about themselves to be bothered about you. For example "urgh so embarrassing the way I speak bet they are thinking I'm weird" change to the way I speak is normal, there are lots of different voices in the world none are weird, that includes mine people don't think anything out of the ordinary about my voice at all, it's just another voice, nothing to get excited about therefore nothing to worry about. Back this up by thinking about how you never go away from a conversation with someone and think about their voice in a negative way. Even if someone had a really unique voice I very much doubt it would take up much time in your head for it to be any sort of issue.
csn you see what I mean? It's like make it so boring it's a complete none issue. The human experience is actually quite common we all go around thinking we must be THE only person in the world to think / feel a certain way. It actually if we're feeling thinking a certain way the chances are many other people are too, we're not as unique as we think and that includes the negative things we think about ourselves. It takes time and doing it over and over again is the only way for it to become a habit.
also things like working on what you need to know you'd be okay IF your partner was to cheat/ meet someone else as that's the fear that fuels your jealousy. So are you working, could you afford to rent someone for you and baby if you needed to, do you nurture your relationships with your friends and family so you have support if you needed it. Don't put all your focus and energy into your relationship you also need other people in your life. Once you know all those things are in place and possible you fear less about being on your own because you know if you have to be you'd be okay, so there's less stress and pressure around what's he doing who's he talking to will that turn into something that means I'll be on my own, because you know you'll be fine on your own.
Hope that makes sense it's not a quick fix it took me months to get better and it's ongoing I have to remind myself. I have a toddler and new baby with my partner so I completely understand you saying you feel vulnerable. Working on all those things will make you feel less vulnerable.
one more thing that helped me was looking at the jealousy with curiosity, where's it coming from, usually when we are jealous it's over something we feel we are lacking, for example I was jealous of my husband's female friend at work who was very fit, she worked out and they had that in common, I realised I was jealous because I would like to get fit and work out so I turned it around to what can I do to not feel lacking and not feel jealous of her I started to workout eventually completely forgot what motivated me to start but it really made me feel good and added something positive to my life so I flipped the jealousy into action. Ok you can't always do this if someone if 6foot and you're 4 foot and are jealous they're taller you can't become tall but you can get curious and think why am I jealous of that what's lacking for me to make me feel jealous of their height.
meditation also helps but that's hard when you have a baby I know.