I think I understand your problem because something similiar happenend to me when I was learning English: You have the vocabulary, you understand everything, you don't have any problems reading or even writing, but when the time to speak comes, your brain just can't work at the desired speed. That means the language is there, you actually got it, but in order to master it your brain need to work faster with all the packages of words and sentences.

There are no shortcuts: You only need to keep practicing more and more until you master it.

One thing that really helped me was to listen to recordings of myself speak. It really helped me identify the areas that were giving me problems.  Once you have those areas figured out you can focus on fixing those. 

Another piece of advice I've received is to not "over think it" when speaking. I know a few who have this issue where they are so concerned about making a mistake they speak slowly because they areorverly preoccupied with using the correct word that the speech becomes disjointed. 

Lastly another good piece of advice I've received is to think in Spanish. It may be a liitle forced at first, but we all have a running dialogue in our head. Have yours be in Spanish. 

These are all things that I've done that have helped me. I don't know if I'm "fluent" but I have been managing pretty well living in Latin America for the last 3 years. 

Good luck!

Jason, I think you're already doing it: force yourself to speak, embarass yourself, but keep going. That next stage takes a long time, and it doesn't matter the amount of reading or writing at this time. If you need to practice producing phrase in real time converation, than focus on doing that.

Think of it as working out. You start lifting 1kg weight, and they're heavy. Your muscles grow, than you procceed to 2kg and so on. The brain is a muscle, after all.

Keep it up!

I suggest you get a language partner here that isn't your girlfriend. Maybe a guy who likes the same hobbies. Someone who maybe it won't be as important to impress or that you won't be as nervous with. If someone else is making just as many mistakes in English as you do in Spanish you can both relax and laugh together about your mistakes. You can even find someone with a lower level of English than you have in Spanish and maybe you will start to feel a bit more secure. Speaking always with a native in their language, you will always feel like you're behind the 8 ball. I say find someone to lighten up with. Maybe find a guy learning English that you can go out and have a beer with, watch a game and yell out stupid things together to loosen up a little. :) You need to be able to relax and not be judged or judge yourself too harshly for the words to be able to flow. When you are relaxed the things you hear often will just pop out of you. When you're in knots and thinking that you can't do it, nothing comes. Believe me, I know! My Spanish can go from great to horrible ... all depending on how relaxed (or not relaxed) I am. The language partners I like the best are the ones where I feel no shame, no pressure and with whom I giggle the most. That's when I can speak the best and I learn the most. 

I hope that helps!

Yo haría caso a tu novia. Leería y escribiría más. Por otro lado, buscaría a alguien que pudiera ayudarme con mi pronunciación y en aumentar mi vocabulario. Buscaría a alguien con quien poder comentar expresiones y con quien pudiera centrarme en el aprendizaje del español. En definitiva, buscaría a un nativo que pudiera ayudarme a mejorar.

Piensa que tu novia, es eso, tu novia. Ella no es tu profesora. Ella puede ayudarte y con ella puedes practicar a diario, pero creo que necesitas hablar con otras personas para hablar de otras cosas y para centrarte en lo que te preocupa en estos momentos: mejorar tu español.