I think I can only invest $100 a month for the next year or two, would that be enough? I am worried about missing big bull market with halving and etf approval.
It's not about being enough, rather it's about being what you have disponible to invest at the currently moment. You are doing what you can to not miss the bull run and your effort is valid. While your colleagues are spending their allowances with drinks, parties, girls, clothes and accessories, you are thinking about your financial future, and that is really honorable.
Feel proud about what you are doing and don't compare yourself to other investors: keep in mind each investor is unique and has an unique reality. The important is to do the best you can with the tools you have under your disposal. There will be always people below and above you in every senses, those are their personal paths, which shouldn't be measured by others for comparison reasons.
Not every students have a mindset focused in investments and long term goals, congratulations! I hope you succeed!