Nice post, I've always liked Dragons. Have you checked on any of the below cards? They're all reasonably priced and may be helpful against the issues you're having

Bogardan Hellkite - Dragon 6RR When it enters the battlefield it deals 5 damage distributed as you chose to any number of target creatures or players. Really nice against the weenie decks and can be a nice little kill spell if necessary. This was the go to dragon in the DragonStorm deck that won the world championships in 2006.

On that note it could use the card Dragon Storm!
A toolbox tutor for dragons that storms... Need I say more? Play along side Seething Song and Dark Petition for free mana / storm count.

If you're worried about early creatures, there are some nice enchants to help with this. Porphyry Nodes at W should help against aggro, even Elephant Grass may be viable against the weenies. Glostly prison is also great to slow down a game until you can get going.

In 5 color I also would maybe add Abrupt Decay in just about any circumstance. Beast Within can also take care of pesky enchantments or anything else. Aura Shards may also be just perfect for a creature heavy deck