It is possible can hack my web wallet?
Yes, of course. everything can be hacked. so if you have a web wallet you should always have a very complicated password and 2FA enabled. If you can use 4 or 5FA I suggest you use it.
Any idea to use 5FA
I think better move to cold wallet. I got bad experience with web wallet, especially bc.i, i set up my pass pretty complicated and 2FA enabled, but at least my coins move without my permission and i lost my coins there.