I need advice

So I really like this guy like I've known him since high school and his been on my radar his one of the people you notice and just look from afar. So recently we've been talking and it's really good his flirting and trying to meet up but I'm hesitant. Seriously my self esteem is so low I'm just really worried that if he sees me he won't really be impressed and that's not the part that worries me it's just like with everything going on festive and all I feel really down on myself I've gained weight and I all around feel like a blob of poop I just I don't know what to do I don't even know what I'm asking just can't someone help me?