I've had two lucid dreams twice now, both have ended not only abruptly but strangely. Help?

Tonight was my second night where I had a lucid dream. In my dream I wasn't paying much attention to my surroundings, but, thinking to do a reality check, I looked at my palms and I couldn't see any lines. I then did the nose/breathing trick. I had to do this several times because I was uncertain. Sure enough, I was dreaming.

I had yelled "I'm dreaming!" before this dream came to an immediate stop. I had woken up. The part that was weird, though, was that I did a little fighting before I was able to wake up. It felt like being in a blanket (pitch black but you feel like there's something covering you) and I was thrashing around a lot inside it, trying to fight whatever was holding the blanket down on me. In the end however, I ended up waking up.

This isn't the first time this had happened. I had a very similar experience before when I had a lucid dream. I've ended up waking up both times, but I was able to go to sleep again in a few minutes. I've heard of being suprised by your lucid dreaming, so you wake up, but I don't understand the blanket situation. I also know you can stabilize to try and stay in it, but I can't even do this before I awake, it's that sudden.

If anyone could help me understand why this is happening and get past it I would appreciate it so much. Similar experiences, advice, etc. would help. Thank you.

It's normal for your first lucids to last just a few seconds. Usually you wake up because you excited. It will get better with practice. As you say, checking out stabilization techniques will help.

When you wake up in a 'blanket', you were still in sleep paralysis. You are in SP every time when you dreaming, so you don't act out your dreams and hurt yourself. It just means, that your mind woke up just a little bit before your body - you wanted to move but your body was still asleep. It's completely harmless. Next time it happens, stay calm and change your breathing pattern or try and move your fingers or toes - your mind will realize you are awake and will wake up your body.

If you read tutorials here in Wiki, you can learn about different techniques to get you lucid and about everything you can expect to happen, including SP. Happy dreams:)

Well you mentioned that you were able to yell "I'm dreaming!" before the dream ended - you would have had enough time to stabilise. That is why it is recommended to stabilise right upon becoming lucid, to prevent premature ending of lucid dreams.
Also, the second part which you mention fighting a blanket, that is most definitely Sleep Paralysis. As Gab says, this is your mind waking up before your body does. Personally, I have never experienced such strong sleep paralysis where I have been unable to break out of it but I would advise you just to calm down and let yourself fall back to sleep. It is not a big deal - your body is put into sleep paralysis every night when you fall asleep to prevent itself from acting your actions within your dream; you are just usually unconscious before this happens. The alternative it trying to mentally will yourself to move small parts of your body while trying to move it physically i.e. fingers

Is it possible that you didn't in fact wake up but fell into a false awakening each time?