ti amo a lot, even with additions that intensify the claim. However, it isn't the exact translation of
I love you de facto, as it is a real intense claim.
Ti voglio bene is a claim you could use more often and even in public joking with your friends, when your partner says some harsh remark that really makes you proud, for example.
DaG accurately explained that you can use
ti voglio bene for relatives and intimate friends as well, while
il mio amore per te è forte is a sentence you'll never hear. You'll probably find it in a grammar book as an example, as it is very unnatural and forced.
I wanted to add the precise meaning of the two expressions. Even if both things are translated to
I love you in English,
ti voglio bene means you feel for that person, hope the best for him/her and feel really sorry when something bad happens to him/her. It's like an empathic issue.
Ti amo adds, to a more intense version of all this, most probably a physical attraction as well, and very likely a sexual desire. It is, again, something you would say to your partner when looking him/her intensely straight in the eyes, before kissing him/her, or when making peace after a minor, or even intense, bicker, to remind that despite some little differences you may have, way bigger feelings unite the two of you, and those can't be mined by tiny things.
il mio amore per te è forte translates to "my love to you is strong". How natural is it in English?