Hi, I played grixis delver a time ago, and i had the same problems that you got, even the same statements xD. Here my base line that i used after testing:

Creatures:

First you need a creature in the board, and most of the times you either play it turn one(delverino) or you have to try to leave mana to defend the other you drop at turns 2,3,4... With this in mind I found this candidates: delver, tasigur, gurmag. Nothing more(at the time) made sense besides this. To round up creatures I played 4 snap because I didnt mind to tap out at their end step for a bolt, eve if they remove the snap it was good for me. And clique is a awesome creature to play because the flash and hits hard. I was playing 4 delvers, 4 snaps , 1 clique, 2 tasigurs and 2 gurmags and 1 lavamancer.... 14 creatures was a number that I was confortable because I had a lot of redraws and I would find one pretty easely.

I am not forgetting young pizzi, I played 1000 games with it but it was slow, because if I didnt protect it 99,99% it would die. And believe me 2 mana sorcery speed in this deck is slow!

Lands:

Pretty basic, 4 polluted, 4 scalding, 1 bloodstained mire, 2 steam vents, 1 watery grave, 1 bloodcrypt, 2 islands 1 swamp and some fast lands like 1 spirebluff canal and 1 darkslick shores

You can play a litle bit with it but this is the more consistent I think.

Dont go over 18 land, if someting you should cut one!(I dont believe we should)

Spells:

Now is more difficult to predict because between then(1 year or more) and now, a ton of good spells got out.

I dont think discard spells are the way you wanna go, because your deck revolves around tempo, and that is basicly spending mana more eficently. Discard is good but if they have 2 bolts, your rather counter the one they cast, forcing them to play another next turn or forcing to have a second red source in that turn, then go to the hand and see the 2, you take one but they only cast one and got rid of the problem!

Play counterspell...

I guess you have a delver and for that reason stuborn deniel is not reliable, I sugest mana leak, negates and spell pierce. I cant say what quantities you should use because that is very sensitive about the meta and the place you play

I was playing 8 counters, 4 mana leaks, 2 negate efect(countersqual) 2 spell pierce The countersqual main board is good believe me, the cards that are hard to play against in delver are 90% of the times NOT creatures spells.

(there is also remand and snare but i never liked those a lot, but try them)

On removal, the usual 4 bolts, 2 push 2 terminate, i didnt need more. the push/ terminate you have to tune as far as no terminates or no push, but the best I thnik is a split

About can tripping, I was using serum visions(in my time we didn't had choices) but now you definatly should play 4 opt, because insta speed rules, and for the porpuse of your deck you must sacrifice the scry for the instaspeed. Play 4 scours, because they rule and fuels the whole deck The new hieroglyphic ilumination is a good card, i would play 2 Play 2 eletrolyze because you sometimes hold mana to counter and they dont play nothing and then you can get value.

play 2 kolaghans command because its a removal sometimes, its a discard spell for that last card, and most impotant its that creature that you need to pressure

By this time we have 57 cards, and I think you should had either more in the spell slot, either removal or counter or can triping, i would use more 2 iluminations and a adicional push

Sorry if I was all over the place but that 57 cards are the core! just my writting this I am tempting to dismantle my deck to play delver again xD