I'm trying to hash transactions together to find the Merkle Root!
There are multiple things that you have done wrong.

First, you hashed just the coinbase part of the coinbase transaction. You are supposed to hash the entire coinbase transaction.

Second, you have hashed the transaction ids of the transactions, not the transactions themselves. Hashing the transaction themselves will result in the txid (ignoring segwit). So instead of hashing the txids again, you just take those as the first hash in the merkle tree and combine them and hash the combination for the second level of hashes.

Third, you reversed the hash hexadecimal representation. You should not be reversing those hashes. However, if you start with the txids instead of the transactions themselves, you need to byteswap the twids first. Byteswapping is different from reversing the hex of the string as two hex characters represent one byte. It is easier to do this when the hex has already been decoded into a byte string.

For combining hashes, you just concatenate them. For the last transaction, if it is by itself, you copy its hash and concatenate the copy to the original. It is just the txid concatenated to itself.