Visitor Visa - B2

I (female, 20 year old student) and my sister (15 year old) applied for a B2 visa to visit my boyfriend and his parents and also do some sightseeing with them for a course of 3 weeks to one month stay. However, in the first interview and application I mentioned them as family friends only. Everything we answered was as per the DS 160 form. In fact, barely any questions were asked. It seemed like because we weren't travelling as a family, we were rejected. We were asked my parents' salary which is 25 lakhs per annum, after tax. We were asked what we were doing, and after all of that, rejected.

My boyfriend and I have been in a long distance relationship for 3 years. It has been a year that we met, and if I do not meet him this year, the next time we meet will be in 2019, due to stamping issues for his Visa. Due to this reason, my sister wants me to get a chance to visit him at least, and I am considering reapplying alone. I do have another year of studies to go. I would like to know if stating the reason as visiting my boyfriend will be a better option, as there is no way I could get married to him and live there now. It is very important for me to meet him, and I'd like to know my chances and it would help if I could get suggestions for what to change in my form or interview next.

I had suggested that the entire family apply together and only I and my sister travel, but my parents consider that risky. Is it okay to do so? Since each person's form is separate.