I'm going to go through the logs (btw thank you for using WCL, so much easier to navigate for me nowadays than WoL.) I will point out uptime problems, and cooldown usage problems.
Now, since swiftmend and wild growth generally go together their amount casts should be based around the max amount of times you can cast swiftmend. Give or take a few based on actual damage being done and time being busy doing other things. Most times, wild growth will have near the same amount of casts as swiftmend, or more. Personally, I like to mix in wild growth between Swiftmend CDs and sometimes hold swiftmend for wild growth, or wait until WG has about 4s left on CD before casting SM, etc. For the most part, I like to use them mostly on CD each, while having a heavy preference for using SotF on WG.
Question: Did you log these fights yourself? Because it has the same name as your MMO-champ name, but the previous fights don't include your druid. So I'm a bit confused on what is happening.
Lifebloom 62% uptime - Still needs major work.
Harmony 95% uptime - Very good. It seems you didn't have it up at the start of the fight, and only let it drop off 2 times. I personally have a very huge (but opaque) aura that reminds me I have 5 seconds left on my Harmony and I should refresh it. Having an annoying remind is a good way to keep it up.
Swiftmend - 9 times. This is not good. On a 7:25 length fight, you should have been able to cast this between 25-29 times.
Wild Growth - 26 times. If you casted this on CD, it should have about 44~ casts, but its throughput goes up pretty significantly (when times correctly too) with Soul of The Forest. If you would have at least casted a swiftmend with each wild growth that would have gave you a decent increase over the whole fight. Since you barely used swiftmend, wild growth in turn should have more casts. (Again, wild growth casts can be somewhat limited based on max swiftmend casts)
Nature's Vigil - 3 out of 4~. This was good. You could have probably used it once more (once for each phase) but its not bad.
Lifebloom - 30% uptime. Very bad.
Harmony - 63% uptime. Very bad.
Swiftmend - 9 times, again. This time the fight was significantly longer. In this time, you should have around 27-33 casts. You're missing a significant amount.
Wildgrowth - 21. Again, use swiftmend before it. Make use of SotF.
Nature's Vigil - 1 out of 5~. Nature's Vigil is a very good throughput cooldown for this fight. If you're healing up top with melee, you should make very liberal use of this when ever you see any kind of damage going on.
Basically looking at these fights, you still have a ton of work on improving your uptimes and using your cooldowns. Since SotF is your talent, its SUUUUUUPER important for you to be using Swiftmend.
Lastly, as a heroic raider you need to try to be very comfortable with your spec before trying to learn mechanics. If you can't do your job unless you're fully focused on your uptimes/CD usage, its going to be very difficult for you to do either. Spend some time in LFR or flex's and try to improve what I've mentioned here. Its really hard to learn a new skill, which is what you're doing here and only practice will improve it.
As per your last part of the post: Overhealing is not gonna matter much unless you're severely running out of mana early in the fight.
About other druids rejuv: You should track them some how yes. You can swiftmend off of the other druids Rejuvs. I use Vuhdo and it pops up with an icon notifying me that the target is "swiftmendable" meaning they meet the HoT requirements for Swiftmend even if its from another druid.