One offs on the sideboard is a little weak. You won't need as much land as you have. Hyena Umbra is stronger then Spider Umbra, so one more of that, drop a Razorverge Thicket. Sideboard your Mana Tithe for Path to Exile, you'll need removal more then Force Spike. Currently Blood Moon is a nightmare match up for you. I'd say drop the remaining Razorverge Thicket and Wooded Foothills altogether for basics. Wooded doesn't add much, to the deck, and razorverge is just not amazing on this low a curve. That lets you drop the basics on the sideboard for 2 more Stony Silence Eggs aren't funny, and no one is watching Affinity, but you can do what fits your local meta best there. The rest is very solid.

I really like the deck, but I feel like it's really vulnerable to counterspells and boardwipes, even if totem armor is there

You could add a card like Thrun, the Last Troll or something like that to help with that. You also have 8 one-drop creatures. I understand that you would want to be fast,but it's something to consider

Anyway, good luck building!

Maybe a Sterling Grove or 2 in the sideboard for g/b/x decks that can attack your auras.the creature count is solid, thrun won't do much for you. The other guy is right about the lands,and mana tithe. More paths never hurts, helps you fight off combo decks you otherwise couldn't interact with. Depending on your meta you might want to play less spider umbra and unflinching courage for Keen Sense To help you to keep drawing gas. Fun deck.

I would replace the Nature's Claim with Krosan Grip for the reason that Krosan Grip can not be countered, unlike Nature's Claim. Krosan Grip may look worse because its two more to cast but if your opponent gets a Chalice of the Void out for one it would be every hard to get it off the field. Stony Silence would not work against Chalice of the Void it because it is a triggered ability and not a activated ability. While Nature's Claim is better against Blood Moon i still think that Krosan Grip would be the better choose. I would keep the foothills in because you need to keep fetchs open to Dryad Arbor to sac when needed. And you really need more Leyline of Sanctity.