I'm at a loss and feeling defeated

Ok mamas. I have a 7 month old and she has been a "bad napper" since she was 3 months old. That's when we really tried to set a routine for her (FTM who worked, didn't know my ass from my elbows) and it didn't work. So we kind of just let her do her own thing, sleep when she wanted and so on. Well about a month ago, I took her to an OT for sensory issues because everything I read said that she basically had all the signs of sensory overload. Fast forward to now, she still won't sleep longer than 45- and hour. On my REALLY lucky days it's an hour and a half to 3. My little girl is so upset all they time, she cries all the time, my husband is getting ready to go out of town for 3 weeks for work and I'm at my wits end! Did/have ANY of you other mamas experienced this and what are some things that helped? I can't take my little girl being so off balance anymore, it's breaking my heart.