I am in fourth year and didn't get to know any of my professors really well. Is it too late to ask for letters of recommendation for graduate school? I am a fourth-year student who graduates in May and I only realised mid last year that I was interested in graduate school. Unfortunately due to my shyness, I didn't get to know most of my professors very well. This is exacerbated by the fact that all my classes are online which makes it even more difficult to connect with professors.  I also cannot find any research opportunities related to the field I am interested in on the university career website.
Is it too late for me to get recommendation letters from professors?
No it's not too late, but you're going to be disadvantaged - mainly because your letter writers probably cannot say much about you that your transcript doesn't already say. They might be able to comment on your coursework performance, but cannot say anything about your research ability, which is going to have a negative impact.
If you're interested in graduate school and can still do some research project, you should take the opportunity.