I don't know if it was the OP or another poster that said they get their hair cut every 5 weeks, so I'm just directing this generally.
If you're getting your hair cut every 5-6 weeks you're never going to get any growth. Hair grows on average (so a lot of people get less than this) half an inch a month.
Unless your hairdresser is only doing the tiniest of microtrims, they will almost certainly be chopping off any growth you've had.
If people aren't heat styling regularly and are taking fairly good care of their hair, then there isn't any need to get hair cut any more than every 16 weeks. If people are heat styling regularly, then going through your hair and 'Search and Destroying' once a fortnight, whereby you stand near a window or natural light, section hair and go through and cut off all the split ends/ breaks you see is a good way to get rid of damage without sacrificing length.
In regards to increasing growth rate, tipping your head upside down for a few minutes every day and massaging your scalp can boost growth, it's called the 'inversion method' if you want to google it.
Biotin can also help, though a lot of people (me included) suffer with spots whilst taking it.
Upping your protein and ensuring you are getting enough iron in your diet etc can also help.
Weekly deep conditioning, daily oiling of ends will keep the hair you do have in better condition, therefore retaining length.