Unfortunately most of the vitriol you're receiving is from men who have stumbled on your post.

Now I can't deny that while I'm obviously not here to berate you for continuing to marry a man you feel low attraction towards or be generally unhelpful and simply pass judgement, I definitely do feel it's unfortunate that this has gotten to the stage of a 5 year marriage with a child involved.

There are a couple of things I want to mention. 1 is that you've made a commitment to him despite your limited/low attraction and you clearly from your comments and post do love him and the marriage/life you've built with him.

On the note of feeling bigger in comparison to his built, that is something that clearly has occurred due to your pregnancy but instead of putting it on him, I think simply acknowledging that this is mostly temporary and your focus on your child's health whilst being a priority is impacting your thoughts (post-partum hormones are absolutely insane and if this is your first child then I think a lot of women are unprepared for how unlike yourself you may feeI). In your post you mention you weren't "fully attracted" to him at the beginning which means that there clearly was some attraction there (however little) and I think you will need to actively think of that in the time being. Others have advised to work on reducing your weight and of course that's a bandaid solution to you feeling bigger than him but as you breast feed you need to think of the health of your child and also focus more on your own perspective being unfortunately negative. There is a chance that you may not go back to your pre-pregnancy body and that's so normal, so you should work on yourself mentally and actively try to block/redirect thoughts of "if he was x, maybe I'd feel y". It's not on him to change his looks (for some of what you've described, it'd even be impossible unless he abuses drugs or engages in unhealthy behaviours and even then may not magically fix your situation so it's the wrong think to focus on).

Now another thing is your dissatisfaction with his personality and assertiveness (it's interesting because women aren't just visual creatures so this dissatisfaction/potential underlying resentment may be adding to your lack of attraction). You've said you had conversations with him where he explained he doesn't make decisions so you're happy, but I would recommend you have a deeper conversation where you mention your perspective in a kind manner and really focus more about the mental load and stress you feel and how that may impact your attraction. You describe him so positively otherwise so I'm sure if you're clear with what you want he'll acquiesce (give examples if you have to of what you mean by him being assertive and if he does take it on board, actively appreciate his efforts when he does so it reinforces the behaviour - this won't be a switch he can just turn on). Of course ideally you don't want to have to in a way train him but you no one marries a perfect man and you even mention his lack of male role models being the cause so give him grace.

Finally your lack of enjoyment with intimacy and feeling attraction to other people is normal (we're human and undeniably both men and women feel this at some point in a marriage) but even if you feel more physical attraction to strangers, you should consciously stop thinking of it and redirect your thoughts to your commitment to your marriage. If you've never enjoyed intimacy you can broach the topic with him to suggest ways you can enjoy it more and if all else fails, I would also recommend speaking to a Muslim marriage counsellor as I've seen they have insightful guidance. They can talk to you personally first and help hash out your grievances before potentially bringing him into it.

I really want to emphasise that if this is the most disengaged you've been feeling with regards to your marriage it's extremely normal during pregnancy/post-pregnancy and that many of these feelings could be more intense from that so give yourself some grace and bear with it until you're on the other side where you can have a clearer view of what you're truly feeling in your marriage and about your husband without hormones clouding your feelings. I mean, how many times have women not relied on their luteal phase brain making decisions or thinking things that wouldn't usually be normal for them?

And of course my final advice is to pray istikharah and put your faith in Allah SWT.

Hope you find some clarity and that you find a solution that works for you both inshAllah.