we don't have the word for "miss". maybe, u can translate "miss" into japanese with dictionary, but i guess there is no concept about "miss" in Japan. u could say "anata ni aitai or anata to hanashitai(I wanna see u or talk with u)" for "i miss u", and "watashi ga koishikatta?(for ur boyfriend)", "watashi ni aitakatta?", or "watrashi to hanashitakka?" for "did u miss me?". :)

I miss you = (kimi ni) aitai Did you miss me? = Aitakatta no?