Yes can you link the recipe?
Sorry if this looks overwhelming but I think it's much needed information. I'm not sure if you steeped the juice or what. I honestly can't tell you to add 1.5% extra flavor and everything will be just peachy or "watermelony" in your case.

I wouldn't add more flavor to the mix as a quick fix, flavors can become muted or taste awful if you add to much! Sometimes you will need extra flavor for higher VG juices as it will kill the flavor a bit. Heres a nice little
guide on flavoring ratios it's short simple and straight to the point. I guess you could try an extra 1% flavor, speed steep, taste, keep doing this until you get what you want out of it.
Again I'm not sure if you steeped the juice, how much experience you have or what, so check this out.
Rip trippers, steeping streething and breathing explained
VG seems to take a while to steep, it's thick and it takes longer for the flavor to "mix up". Put the juice in a box, closet, drawer ETC, It needs to sit In the dark, at room temperature. The time period can differ depending on the juice, generally a period of 1 week to 1 month! I've heard of some juice taking months! This seems to be what the majority use if they have some e-juice ready to vape on. This method may also help you in the future because you won't have to guess how long something needs speed steeped or what exact process you used. I would recommend writing down the steps YOU took if you decide to quick steep / speed steep your e-juice. Did you shake it every 2 hours did the heat fluctuate, what flavor took 1 hour which took more, see what I mean? I would also recommend you write down the date you made the juice and make a log of how it tastes every week or so using the slower method.
In the rip trippers video I posted above he says fruit flavors are generally ready to go after mixing. I used a 50/50 mix of strawberry @ 18 mg of nic and it didn't taste the best right off bat! After 10 days, It's tasting very good. I also left a few ml in the bottle so I can test it every 7-10 days.
There are a number of ways to quick steep / speed steep, I'll list a couple*.
-
1.
running it under hot water for a while or putting it in a cup with warm / hot water. ( not to hot I believe anything over 135/140F is bad!)
2.
crock pot - ultra sonic cleaner (Again not to hot!)
Other resources
Master Techniques
General Steeping info dannyv45 blog
There is so much information on this forum about steeping, I've heard just about everything. It's a learning process and once you get it right it's very rewarding. I'm sure someone else will chime in on the subject as I'm rather new to mixing myself. I found using peoples already created recipes to be a great start then you can start tinkering with different ratios and flavors! Best of luck on your endeavors!