You can go to classes until your head spins (as it seems to be doing

) but it won't get you anywhere past a certain point, as far as getting past getting started. The only way you're going to become fluent (even conversationally competent, let's say) is to speak and listen to the language. Classes twice a week won't get you there - it needs to be constant (at least several times a day for extended periods) before it starts creeping into your brain.
And I have to say - 18 months is a LONG time to be in classes and not feel like you're advancing to conversational-level Spanish.
Learning a language is different than most anything else you will learn because you are changing a different symbol-link to concepts and objects set in your mind since you learned English as a baby and your brain is having to translate everything between two symbol sets. It's a lot of work and doesn't feel natural and how can you actually carry on a conversation if you're translating both sides of the conversation both ways?
Once you've got a pretty good handle on HOW things work (that's why I like structured grammar classes to start with), you will have to speak and listen to learn more. Doesn't mean you don't need to expand your vocabulary, and go back to the verb conjugation charts from time to time (even often, at first) to remember simple present and future, for example. Once you have the three most important tenses down and start talking, you can go on and take a tense at a time, later. You'll be surprised how easy it is once you really get going.
Talking in infinitives and present tense is fine to start with, but people will tend to think of you in their own terms if you can use just those three simple tenses - present simple, future simple and past simple - and conversations will be there. Other tenses will come with time.
As to how to get there?
TALK in Spanish at home more. Doesn't have to be every minute, but maybe even a majority of the time. And your children, you can get them in a bilingual school if that becomes a problem later, and even change the speaking habits at home back to English once you get familiar enough with Spanish. One of my sisters-in-law and I speak English together all the time now, while she talks Guarani with the family when I'm not around (I'm still trying to get someone to teach me Guarani - thinking about taking a class at CUI) and we all talk Spanish when we're all together. It's not hard to mix it up.
THINK in Spanish as much as you can (this may be one of the most important tips, in my opinion). That's where it's really important - your subconscious mind needs to KNOW what the words mean, which tenses to use, which pronouns and gender to use, etc. At first, you'll be translating in your head but after a while, you'll realize that you're no longer searching for the right word or tense or gender, that it just starts coming naturally. It's hard to do sometimes, and obviously, when you're working or in other concentration-heavy moments, you won't be able to do it (at least at first) but do it when you're walking, have imaginary conversations with yourself, name things you see, etc. Any time you're forming words in your head, and have the time, try to do it in Spanish. Make mental notes of the things you couldn't say and look them up later.
WATCH as much TV in Spanish as you can. And/Or, what helps me often (vocabulary and usage because I'm VERY visual as well), is watch English programming that has Spanish subtitles and READ the subtitles, every one of them, almost religiously. I did that for so long that I can't watch anything in English any more without reading the Spanish subtitles as well, when available.
DON'T worry about making mistakes. DON'T worry about perfect pronunciation (although I do believe it's very important to understand, letter-by-letter, how they sound and how to speak and WORK on it) but you don't have to be absolutely perfect. Talk slowly - it doesn't make sense to try to speak with native speed when you are having problems pronouncing the words. Accept that some people will have an honestly hard time understanding you at first, and you'll get to know after awhile when they should know exactly what you said

Easier to improve pronunciation once you are not translating everything in your head as well.
I came here in 2006 with Spanish unused for more than 30 years. I'm now in my early 50s. I had two years of Spanish in high school in the late 70s. I was never fluent, although I could converse (in a simple fashion) with the Mexicans on the labor crews where I worked after high school (couple of years). When I met my wife here, she didn't speak real good Spanish (she's from Paraguay, from the poorest area, where the predominant language is mostly Guarani with a smattering of Spanish mixed in), although she was much better than I was (she was actually conversational, just with poor form). We got along alright at first, but the more complex that became our relationship, the more we needed to be able to speak the same language well. Hell, we started off with me using Google Translate on the computer! I never took classes here, although I did try some online things (Rosetta Stone primarily - I suggest it or something like it for people who are very visually-connected), which helped for vocabulary mostly. I reviewed the conjugation charts often, available for free online. Within months we were having conversations without Google and other crutches.
Now, many people here think I'm either Columbian or Mexican, or sometimes Brasilian. About the only time I have a hard time being understood is by taxi drivers who are "rompiendo las pelotas" (breaking the balls) of a foreigner. I'll never speak with an Argentine accent because I learned originally in Texas and with Mexicans, and I don't know that I would say I'm 100% fluent but I speak about 90% Spanish and 10% English on a daily basis now.