Rare evening practice

I just finished my today's Ashtanga practice. On the weekend I didn't manage to get on my mat (shame on me) and therefore I really missed an extensive practice with enough time. So I decided to move my today's practice to the evening. In the morning I only practiced some pranayama and a few soft poses. The whole day I have been looking forward to the practice and barely returned from work I changed clothes and jumped on my mat. My boyfriend hasn't yet returned from work, so I had no distractions.
The practice was on the one hand very good. I was quite focused, managed to concentrate on the breath and really felt a connection between the breath and the heat/energy level. On the other side I found it so hard and exhausting. At first I planned to practice full primary but when I reached Navasana I was already so worn out that I said to myself 'ok, that's it, enough for today'. Then I did Urdhva Danurasana and Finishing. Despite practicing only until Navasana I spent nearly two hours on the mat. I took it very slow and added some extra-poses.
And I couldn't avoid to have a feeling of slight frustration during the practice. I don't know exactly why, probably because I sometimes have a feeling of never moving on and always remaining at the same level. Of course my sense says that this is not true, but sometimes it feels so. It's hard to notice any progress if you're always on your own. Also I'm not so good at motivating myself if I'm always on my own. Ok, enough whining, the next workshop will surely come and give me some extra-motivation.
Right now I'm thinking about visiting a Yoga Retreat at the North Sea in summer. It is guided by my two favourite teachers, so this would sure be great. Let's see ...