I probably would have been a bit higher on the bakery and cream side for my own personal tastes with TPA's as I find I struggle to taste their flavours, bar in my personal opinion the horrid Rainbow Drops, unless they are above 8%! Yeah, a good 4wks to properly bring out custards and creams. I mixed up a couple of Boston Cream pie with custard and cream and a Choc Glazed Doughnut 2 wks ago and will wait another 2 before my own personal verdict.
Any bakery, cream, custard deserves at least a month to come together. For sweet I use 2 to 3 drops of Cap Super sweet per 30ml. I like my sweet too. Id be about 3% higher on those TPA's, but that's just me. Exercise some patience, they may be ok to you, if not go higher a few % points. Can take a while to sort your diy out, and even then you still keep learning. I still am from the guys on this site. It's worth it though. Good luck mate.