@Raphael is absolutely right, catchall + forwarding is a death sentence to your mail reputation - avoid at all cost!
for gmail the solution is quite simple, receive your mails (catchall if you must) in a local inbox and use gmail to collect these mails via pop. it will still sort spam into spam, but not reject stuff, which would lead to backscatter etc.
you usually also can set up smtp for your mail-account in gmail to be able to answer/send out mails with the correct mail-address from your own domain then within gmail.