Is there any way to find answers I liked (clicked the heart button on)?
Technically yes, but...
... it can be a bit tedious, depending on how far back you want to go and on your activity on the site.
All the answers that you liked are listed on your profile page in the Activity tab. When you click on a red heart, the following event is added to your profile page
#["your display name"] quad "said thanks for an answer to" quad ["the name of the question"]#
So all you have to do to find these answers is scroll through your activity history and look for similar events.
Now, this is far from ideal because if you want to find all the answers that you ever liked--or a particular answer that you liked weeks or months ago, for example--you will have to do quite a bit of scrolling, depending, of course, on your activity.
So you can track down the answers that you liked manually, so to speak, by actually looking for them on your activity page.
If you want an easier way to keep track of the answers you liked--or any other answers/questions--you can add them to a collection
This will get all the answers on a list that you can access anytime you want, with no scrolling involved! :D