If there were other non-supervisory higher level developers you worked with, and assuming you have not already been grumbling a lot, you should ask them "As a newbie, honestly, how do you think I did on this project? Was I helpful to you guys or mostly a PITA? How much (not "any", trust me the question is or should be how much) of my code did you guys just throw away completely or rewrite?" Etc Etc.
If you have already been grumbling too much, too late, others will no longer want to get involved. But you may want to at least do a thorough code review and see how much of your stuff made it into the final build.
What you think with one year experience vs the reality may be dramatically different. And if you are any good at this, one thing is an absolute, much later if and when you look back at this code you will realize in no uncertain terms it was absolute sh! oops sorry, "it smells really bad".
The client may be "happy" now they probably have not even used the stuff yet. It's called full life cycle experience. Having to support the probably much less than fragrantly aromatic stuff you have released will be much more enlightening than writing it the first time.
I'm gonna be brutally honest about some things here. If it were really a large scale project, and you genuinely even saw much less touched anything even close to 80% of it in 5 months as an entry level developer, I hate to tell you but there is a very real possibility they were moving you around a lot, or just let you do whatever, because they felt like the could not get any meaningful work out of you.
Hope that you are just making the almost universal inexperience mistake of grossly overestimating your real contribution instead.
I think it is pretty safe to say this is a fairly naive question so I am guessing your are career world, not just IT entry level, i.e. a youngster. I will not mince words. The rest of this is gonna seem harsh maybe.
Nobody ever said life was fair. I don't think anyone with any kind of sense has ever said life was even supposed to be fair. It's called paying your dues and right now learning anything you can learn, both good and bad, should be your only concern. No matter how you are treated, consider yourself fortunate to have the opportunity to make something for yourself.
And you are fortunate. Sure you probably have accomplished some stuff. But you were lucky to be born with enough resources to learn a science, and if it was not your parents directly it was certainly your elders and the grace of your existing social institutions that deserve most of the credit for having gotten you this far along in being able to use that ability. You are already way on the hot end of the fairness in life curve, believe me.
No one can advise you on whether to stay or go, but I will say this, if not this job, the next one - you gotta stick one of the early ones out for at least a couple, preferably a few years. If someone comes to me with three + jobs on their resume, no matter how good I think they are if none of the jobs is clearly something close to full life cycle experience I will tell them to come back when they have that - still just too much they can't possibly know yet.
As far as the time off, not enough info. Maybe you could have in fact worked it out - did you not have any vacation left? It is early in the year for vacation. Maybe you did not ask soon enough and they are just one of those companies that are just stuck on protocol. Maybe you asked like you were supposed to and they could not spare anyone else and you got bumped for seniority - tough break but ... Maybe they even did you wrong.
Hey whatever. I am all about respect and praise and environment, to the point where I am willing to sacrifice considerable financial gain. But With one year experience you've actually earned enough real standing to maybe say "Yessir, thank you sir, can I have some more of that sir." I have eaten literally months - most in fact of my total vacation time over the years because a business just could not spare me the time. Mostly by my choice. I've gotten a lotta thanks but even now, no one has ever said thanks for that. Now if I need time I need time. I never absolutely need but so much time at any given time. And now I mostly try to take my vacation, although I usually have to do it at Christmas, but I like that and nothing ever happens then anyway. I am also not some kid fresh outta school either though.
If you are really "too honest and dedicated" this all should not bother you much. The thing is, we did not hear anything about what you might could have done better or things you might have not done well or mistakes that you made, and so you should be able to understand why many people will have some healthy skepticism.
Oh, and as a stranger on the internet, I stand by my advice. Take it. People never like it and never take it - that's how I know for sure it's good, I guarantee it, lol ...