Is this the end?

This is the first time I've posted on a forum so please bare with me, but I am looking for some advice..

I started dating this girl a I work with a couple of months back, (I originally turned her down but shortly after began having feelings for her and eventually plucked up the courage to ask her out). It started really well, we took it slow, meeting up a couple of times a week and texting most days and didn't get physical for 2 months. Not long after we decided to make it official and for the first 6 weeks everything was great, we saw each 3 or 4 times a week and spoke everyday, I loved spending time with her and knew that she did too.

However over the past couple of weeks things have taken a bit of a turn, it started out as a minor issue, she was off with me at work one day and after making plans to go out that night, I could tell she wasn't really up for it and she eventually called and cancelled. Ever since then I feel like things have changed. We still meet up 2-3 times a week and text each other everyday, but I feel like there is less warmth from her and it feels like I am making most of the effort. We used to text continuously for hours and now its a a text or so an hour and I feel like she is always annoyed, like it s a chore to see me.

Its got to the point where I have now asked a couple of times if everything is OK, both times she said she was having a few bad weeks and is it was nothing to do with me and she was really happy with me.. but I'm struggling to believe this. It came to a head a couple of days ago when I asked her out right if she wanted to break up, she said no and apologised for how shes been with me, but after expressing how I felt about the situation I'm still not getting much warmth back.

I might (probably) be overreacting over this but there are several reasons for this, I haven't been in a relationship for five years and after that amount of time of being alone I guess its hard to understand the ups and downs of relationships, this is also my first relationship where I have been more into the person than they are, It scares me how much i like her and that suspicion that something is wrong is really worrying me, also as you can probably tell I'm a massive over thinker, I over analyse every situation no matter how small and manage to put a negative spin on things.

All of the things I've been over thinking are so petty and minor that Its embarrassing when I talk about it to someone as I think I'm overreacting but cannot stop thinking about it. I want to make sure things are OK, but I als don't want to smother her and push her away.

So I guess the advice I'm seeking is I am overreacting, is it just that she's had a few bad weeks and just isn't in the mood to be warm and chatty all the time or is this the beginning of the end where things will ultimately just peter out?

Any advice positive or negative will be appreciated.

Thanks.

man you just way too much overeacted and nobody likes a clingy person but it also shows that you care which is good and remember starting of every relationship is like heaven but after sometime it just start to fade and it's totally norman and happens in every relationship so don't overthink by that you are just going to make it worse, till now nothing is gone bad and by knowing your history with her you both will get over it for sure just tell her a sincere sorry for your recent behaiviour and tell her to talk to you whenever she is fine with it give her time for absorb the situation and to calm down, she will be back in no time just stop pushing her to the edge and tell her she can take all the time she need, do it over a single msg or call or casual meeting and give her some space and everything will be back to normal in no time, i hope this helps believe me this is not the end and you both will come back even stronger i hope

Short but precisely help:

Man relax. Dont take everything too serious :)
I know that she is important for you but the more you put her under pressure the more she will react in a comical way :)