You're probably being underpaid even for Latvia. The first thing you should change in your analysis is that you should compare your salary to other software developers, not the general national average for all people. I would hope that the Central Statistic Bureau of Latvia provides this data, but you'd have to search for it yourself.
I'm from Estonia (immediate neighbor of Latvia with a similar history) and the statistics here [1] paint a healthier picture. The median software developer salary in Estonia for Q2 2021 was 3300€/month (39600€/year), with the average being even higher (3460€/41520€). These are national level statistics, so the numbers are even higher if you work for one of the local unicorns or Microsoft.
You should probably start demanding more money. Not US levels of compensation, but at least figure out the local Latvian median for software developers and aim for that to start with.
Salaries in Lithuania are about the same as Estonia, however I've heard of contractors getting nearly €10k/mo (before tax). Even working as a shop assistant you can get up to €1500/mo, so yes I would say OP is very much underpaid.
I'm from Estonia (immediate neighbor of Latvia with a similar history) and the statistics here [1] paint a healthier picture. The median software developer salary in Estonia for Q2 2021 was 3300€/month (39600€/year), with the average being even higher (3460€/41520€). These are national level statistics, so the numbers are even higher if you work for one of the local unicorns or Microsoft.
You should probably start demanding more money. Not US levels of compensation, but at least figure out the local Latvian median for software developers and aim for that to start with.
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[1] Search for "Software developer" at https://palgad.stat.ee/en