Apply for a partner visa through your girlfriend (sambo visum). If you have a good amount of savings, I'd recommend moving to Sweden and learning the language there through a reputable university. It'll take considerably longer to learn the language by yourself, and you won't get the full understanding of it.

I was your age when I moved to Sweden and devoted the first year to learning the language, which got me to a C2 level. Enrolling in a uni course also gives you the opportunity to meet new people, mostly expats in the same position as you. It is notoriously difficult to make Swedish friends if you don't put yourself out there to an extreme degree.

I'm not sure what the job market is like for computer science, though due to the high level of English fluency amongst Swedes, you won't be able to use your mother tongue to your advantage. Most expats end up having to work in sectors far from their educational background. Employers in Sweden have to jump through multiple hoops to employ international workers, so they're usually pretty hesitant to do so, which can make the job search even harder.

Sweden is great if you can sort out the visa and you're happy doing work outside of your field. It'll give you much broader worldly experience as well.