just need an advice!

Hello everyone.
I‘m new to this forum, I find it very informative and friendly, so i've decided to ask for an advice.
I have two small angelfish (about quarter sized bodies) in a 12g eclipse aquarium plus two otos.
The tank is heavily planted with various anubias species, cryptocornes, dwarf sag, mondo grass and anaharis.
I do weekly 30% water changes and everything seems to be going great.
I know that the angels are growing; I also know that they are slow growers. I can’t sex them at the present time, so there is a 50% chance that I have a couple.
For how long do you think I could go on like this until the tank is overcrowded or I have territory issues?
I also don’t think I’ll be able to get a bigger tank soon, so when they are bigger I guess I will have to say goodbye :sad
I am really attached to these guys, I know I were not suppose to buy them in the first place, but I just couldn’t resist their beauty and now I don’t know what to do!!!

Any feedback is greatly appreciated,
F.

thank you for the reply
i was thinking about upgrading to a 25g tall, this is the most i could fit into my apartment :mad2
but what if my angels are the same sex?
i suppose this may lead to some serious fighting ones they mature (even in a bigger tank).
what should i do then? keeping just one angel?
there is another plan i was thinking about:
maybe i should get another two baby angels for my 12g, same size as mine, and hope that there will be a pair (the chances would be pretty good).
after 6 month (or whatever time they'd need to grow) i might just keep that pair, moving it to a bigger aquarium and give away the other two.
what do you think?