I suppose = 見受ける ("I guess" can be used in the same way) Example: I suppose I should go to bed earlier, since I was late to work yesterday. 昨日遅かったから、もっと早いねて見受ける。 I think can mean 思う or 考える Example: I think that you are nice. あなたが優しいを思う or, I am thinking about what to do tomorrow. 明日するを考える I feel can mean 思う (just like "I think") or 感じる I feel happy today. 今日嬉しさを感じる Sorry if my translations are strange, Hopefully this explained it!

they all have the same meaning. "I suppose" (估計）has less emotion, I feel (我覺得) is usually less used and means a bit more emotion, “I think” is just how you see it （我想，我認為）. i know you are japanese, but maybe you will know some of the chinese meanings ... above

What is the difference BETWEEN these?