Hi nak, big decision..........and telling your friend has probably made it feel more real for you or more of a commitment so naturally you're going to be a bit unsure about your feelings in general (?) or feeling things a little more (?).
And while it is really good that you seem to be taking things seriously/they're having an effect on you. maybe have a little more confidence in yourself/your decisions/where you want to go from here. And even trust your instincts or follow/trust your heart a little more??
If you want to go with forestry, if it feels right for you then go for it!! If not though don't worry about what you've told your friend or changing your mind, it's about what's right for you.
And hey, if you're really unsure/feeling pressured, just give yourself a bit longer to think about things, take your time. Nothing has to be now when you're thinking about something like that.
Alison