I really need some help with letting go

I've been struggling recently with letting go of 'success'. I feel crummy unless I'm working towards something and unless I appear to be doing well. It's awful, because it's not me at all. I feel trapped by this desire to "be someone". Every time I try to let it go, the feeling always comes back. It's like "stop messing around, time is ticking away, you have to accomplish things". So I cycle back and forth from just doing whatever I want and then taking rigorous control over everything by literally planning out my every minute of the day to "make sure I'm a success". It's insidious. I understand on a conscious level that I don't need any of these things to be happy and that in fact, all they're doing is making me more unhappy, but I'm having real trouble letting them go. I guess because some part of me feels like I will have nothing if I let go of all of these bullshit things that used to mean everything to me.

I want to live in the now and be happy with my life right now, rather than always looking to the future for happiness. I'm struggling so much with this though. Those of you that have overcome this, do you have any advice?

Edit: Today I've been trying to just go through the day doing what I want, rather than doing what I think I should do in order to 'progress' and I'm discovering that I really don't even know what I want because everything I think I want has some BS superficial reason behind it. I can't figure out what I want, when it doesn't involve either impressing someone else, looking good or appearing to be good in some way. It makes me sound like a vain person, but I'm really not. I'm actually the opposite, I'm shy and kind and I love to help people and I rarely even focus on myself, which is the irony in all of this. I think I've just been so conditioned to do what is expected of me that I've lost entirely who I used to be before any of that happened. I need some serious help, I feel like I have absolutely no idea how to just BE :(