Nah don't worry man, all that is normal, you just have to take it as it comes really, first time I had sex I didn't come and honestly I still have a lot of trouble reaching orgasm, I can happily fuck her for hours (or until I go soft -- this happens to me also and I consider it not a big deal)... but if I want to come I have to really concentrate hard on a sexual scenario of some kind (focuses my brain and prevents overanalyzing, the same thing you complained of) and block out everything around me and I often lose concentration as I get closer. I'd like to be more mindfully having sex, but at the same time this is what works for me. What I suggest is just keep doing what you're doing.
What can help with the going soft during sex is (1) be in a position and in a rhythm that you really do find pleasurable, if you start doing it "for her" then it is easy to go soft since you're not focusing on your own pleasure (2) use visualizations, if you just visualize a big hard dick (say a dick carved from wood) and focus intensely on that image while fucking then your subconscious will do the rest... another visualization I really like is to imagine her walking my baby in the park in a stroller, sitting down in a nice shady spot, lifting her sweater and breastfeeding my baby et cetera... I can construct a story around this and it blocks out any negative thoughts or overthinking, PLUS, signals to my subconscious that I have already dumped a load in her, my subconscious then takes over from there and strives to make the information I've given it true.
Having said all that, you only really want to use these kinds of techniques if there is actually some issue you want to deal with or changes you want to make, the most pleasurable way of having sex is simply just to be in the moment and experience the sensations without thinking, just letting them wash over you. But this maybe a bit like reaching nirvana, if you are good at meditating and have excellent mental control you could achieve this, but for ordinary people it's more like something to strive for. Another thing that really helps with enjoying sex is to have an abundance mentality, once you reach the point where you can get sex whenever you want and it's not such a huge deal it's, I suppose, kind of like sitting out in the sun on a sunny day and drinking your morning coffee... just a pleasurable activity that you enjoy as part of your day.
Another thing to keep in mind is your mood really changes during a sex session, initially you might be quite stressed from a busy week, overthinking shit, worried about financial matters, or your relationship with your partner etc... this happened to me a bit last night, was a bit in my head, not super hard (luckily she was as horny as fuck and I ended up doing a soft entry and getting hard inside her, which worked well)... and you know, my mood improved a lot, in fact 2.5hrs later we were doing a round 3 and I could not come, she sucked my dick for like fucking ages and then gave me a handjob for further ages and it felt fucking great but I couldn't stay focused enough to come, however my dick was as hard as a rock. So this was pretty good considering how things started (I finished myself off eventually). Just STICK AT IT, NEVER BE DISCOURAGED BY ANYTHING THAT HAPPENS, persevere and you'll get into it.
Ray
PS Why get a vibrator... well they're just generally awesome, but if you're having trouble getting her off then you may need to get the big guns out. In my opinion
these are the most powerful and reliable vibrators if your goal is to get her off as quickly as possible, I have never owned one but they have them in love hotels in Japan and also my Japanese LTR girlfriend had one which she preferred over any of my vibrators (they don't penetrate, it's for clitoral stimulation)... I absolutely guarantee that despite any issues she may have had in stimulating her clit in the past, this vibrator will definitely do the job.