Sorry Inari but your tank is full and will be more than full when the bristlenose gets grown. A bio-wheel might help better support the bioload you have now but it won't allow you to add more fish. Right now you have in adult size (remember when stocking a tank to figure adult sizes)
3 speckled corys = 6 inches
2 pandas corys = 4 inches
1 albino bristlenose=5-6 inches
1 oto =2 inches
1 betta = 3 inches
Total adult inches =20 inches of fish
The shrimp don't add enough of a bioload to even count unless their are an awfully lot of them.
The bristlenose is a real poop machine. The tank sounds really pretty but I wouldn't add anything more to it.
The bristlenose is a good excuse to get another tank and give his other bottom dwelling friends more room( you know any excuse to get another tank

)
Carol