How come I have more Steem and now my vote counts for nothing?

There are various possibilities here due to the different elements that affect an individual's upvote value:

• 1 Price of Steem: The value of Steem has reduced over 2018. When the Steem price goes down all vote values go down.

• 2 Voting power reduction: When you vote your voting power reduces and it takes time to recover. If you vote more than 10 times a day then your upvote value will be reduced until your voting power gets back to 100%.

• 3 Overall SP being used to vote increasing: There may be more Steem Power being used to vote in total than before. If the central Steemit team or large whales delegate more SP out to users then there could be more SP being actively used to vote overall (the central Steemit team does not vote). More SP being used to vote means each user's SP earns less of the reward pool.

• 4 Loss of Steem delegation: Each new user gets a delegation of SP on starting with the Steem blockchain (typically 15SP). However this delegation is removed over time. You may have earned some SP since starting but lost this initial delegation, offsetting your gain of SP.

Looking at your Steem wallet, since you started just before the high in the Steem Price, my guess is a combination of mainly 1 and 4.