I'm hoping some of you hard core Demon's Souls players can help me out.  I have beaten the first two demons in the first level (the big blob with all the little blobs covering it and the Tower Knight) and I have beaten the Armored Spider in Stonefang Tunnel.  But here's my dilemma:

When I beat the first two demons, I consumed the things they dropped so I could get a bunch of souls and didn't realize that you can trade those in for awesome spells.  Now it seems I have missed out on the Total Protection spell.  I have kept the one I got from the armored spider because I don't want to miss out on any more of these things, but am I going to be able to finish the game without Total Protection and/or is there any other opportunity to get that spell? 

The thought of starting this game over again breaks my heart.  I have 20 hours invested in it already and have done a TON of grinding.  I have a powerful enough character built up to have beaten the armored spider in one try, so I'm reluctant to erase all that hard work.  Am I screwed? 

TP is a huge plus, but you dont need it...push forward

Yes you'll be fine. Later in the game you can get the spell warding which beats the shit out of total protection. You'll be fine just don't consume those same souls when you go into NG+.

What's NG+?

after you beat ghe game you unlock New game +, New game ++, then New game +++

I imagine those are just harder versions of the first run through?

absolutely, but you keep all your stats and items( except story related items) and you get the stuff you missed or accidentally consumed

You just won't be able to redeem those souls in your first playthrough, that's it. Just don't convert the rest into souls and you'll be fine.

At what point do I get to start trading those in? I hung on to the one I got from the spider. Who do I give it to? I went to both blacksmiths and neither of them offered the option.

but my god,

New game +, New game ++, then New game +++

what is the point to continue to play ?

is it to get betetr stats/equipement and become more badass killing the boss in 1 shot ?

or is it really more challenging and so, interesting .... ?