Good translation of your sentences is more like:

Je l’aime trop. Ça m’impressione trop.

si cannot be used at the end of a sentence.

No, “si” can’t be used like that; with “tant” and “tellement” a continuation is needed.

• Ça m’impressionne tant/tellement que je ne sais pas quoi dire.

If you change the punctuation “tant” and “tellement” can be used in the end, though (ngram1, ngram2, ngram3).

• Ça m’impressionne tant !
• Ça m’impressionne tant…
• Je l’aime tant !
• Ils en voient tellement…
• Elle le veut tellement !

When placed in the end, as shown above, “tant” and “tellement” receive usually a special intonation (pronunciation with more strength and special intonation).