Your language and general discourse with your manager sounds all wrong, tbh. From both sides.
For starters, describing yourself as a “burden” is emotive, and that things “got heated” is not a productive or healthy workplace dynamic.
Strip all of that stuff away.
Your workplace should have an existing and up to date risk assessment. If it’s a good and adequate one, it should have risks for pregnant women included. Ask to see this. If there isn’t one, clearly and concisely write the ways the working practices that are now dangerous or unwise, and highlight in particular the ways that those practices have changed since your pregnancy announcement, and the difficulties that this causes. Keep it factual and non-emotive. Eg (and I’m not quoting directly here, I’m making this up to demonstrate “Official WHO guidance is that pregnant women at X weeks should only lift up to Xweight. I’m frequently required to lift in excess of this, and the new ‘sole working’ shifts mean there is no one to call upon for support’. Highlight this, in writing and ideally to HR/boss’ boss, asking for a risk assessment incorporating your needs as a pregnant woman. Question why lone working has been introduced since your pregnancy announcement (for lots of businesses this breaches insurance terms, your higher up bosses might not be aware of these solo shifts).
This is your company’s turning point to either realise that decent employers would not take this approach, (or that your line manager is handling things all wrong) or you to build a picture of burgeoning discrimination, which will probably just get worse if things go unchecked.
You need to keep a clear head, and, IMO, your manager needs training in how to conduct a proper and worthwhile feedback session.