Ok the 5 Pearl Gourami (beautiful fish - I have 2 myself) will soon be about 5-6" in size and they are thin but still rather hefty fish. You don't say what specific species by your bristlenose are but my two will eventually end up about 7" long . I'm worried about 5 Pearls in a tank together - it kind of destroys the effect of their beauty when 1 or 2 should be the star of the show. And they just grow too big - that's all people will notice.
I always do a 50% water change every week regardless of how many fish I have. I have one tank with only 6 big fish (in too small of an aquarium) I have to do 2-50% water changes each week to keep up with all their poop (admittedly some times I skip one of the two water changes and just do a nice suction on the gravel - which is about 20% of a water change.) But all the fish in that tank I found out the hard way were aggressive so they all ended up in this tank together - they really need a 55 gallon tank instead of a 29 gallon - one of the fish is 8" LONG. (spec's say 5" max - I must be giving him super growth food). All but one are Gourami's and the 6th is a Cichlid that a pet store owner lied to me about being a "chocolate gourami" - she's 5" long with huge eyes (gouramis don't have big eyes) but she does have a classic Gourami spot on each side. Small town local fish store owner that's supposed to be amazing turned out to me to be a liar and an a$$hole - nearly all the fish he sold me died - she's the only one left after 4 months and I bought 6 fish. Refused to take them back since I had done an emergency water change when the fish all started dying.
I've also read somewhere - possibly here, that plecos are big poopers so if that's true then you will be doing a lot of water changes. Why 4 of them - aren't 1 or 2 enough?
Personally I don't think your tank is overstocked but I think if you add angelfish you are going to be waay overstocked - they are fairly sizable fish too. Plus Pearls can get a little aggressive (especially towards new fish) I would hate to see your angelfish fins in shreds. If I were you I would look at rainbow fish -subtle beauty. Or some of the small gourami like the honey ones, or the chocolate (probably only available online) Then you will definitely be overstocked but not to the point where anybody but the Pearl Gourami will feel it and that's because 5 Pearl Gourami are going to take up a huge part of your tank - if you could give 3 of the Pearl Gourami to somebody I would be a lot more comfortable about the number of fish-- they don't need to be in a pack and they'll just fight. Big Gourami's, as a rule - with a lot of exceptions - tend to be semi-aggressive. In fact whenever I've had multiple Gourami's of the same sub-species they seem to squabble a lot - 2 are ok - 3 or more is a crowd.
Also, if you're worried about it, none of my dwarf gourami's have ever caught whatever disease people talk about and I have a LOT of dwarf gourami's - So I wouldn't worry about it unless you're buying your fish from a place that looks like it doesn't have healthy fish or clean tanks. Gourami's don't seem to need identical companions. I have read that they like to have one other one like them, but no more. That seems to be my experience and even then some just fight whatever sex they are. Grumpy fish but not serious fighters.
My tanks are all 29 gallon and I have something like 2 Pearls, 2 plecos, 3 cory, and 5 tetra and 5 raspbora (about 1/2" but very pretty), 2 very small dwarf honey gourami's (max 1 1/2") and 2 chocolate gourami (max size 2 1/2 inches - and I'll believe that when I see it - they are about 1/2" right now). I think I'm overstocked but just by looking at the tank it sure doesn't look overstocked. I have ground feeders (plecos and cory), I have middle of the fish swimmers (Rasdoras and the Tetra's) and the gourami occupying the middle to the top of the tank. The pleco also keep semi out of site most of the time. So it doesn't feel or look at all crowded - but that's only part of the problem - this many fish POOP A LOT plus they take different foods, so I have a tendency to overfeed to meet everybody's needs (I have some herbivores and some need supplemental algae tabs). All that food makes a real mess
So think of your tank in terms of where everybody spends most of their time so they aren't all fighting for the same space AND think of the amount of waste these fish will be generating. To me anything less than a 50% water change is just a big waste of time unless all you are wanting to do is try to get all the gravel clean - and even that may take 30-40% with that much waste. Also my tank with all larger fish is just boring. This tank with the variety of species and colors is so interesting - you'll always see one pop out from nowhere that you didn't even remember you had - and for a visitor - much more entertaining.